qid int64 1 4.65M | metadata listlengths 3 3 | prompt stringlengths 31 25.8k | chosen stringlengths 17 28.2k | rejected stringlengths 19 40.5k | domain stringclasses 28
values |
|---|---|---|---|---|---|
251,296 | [
"https://security.stackexchange.com/questions/251296",
"https://security.stackexchange.com",
"https://security.stackexchange.com/users/122309/"
] | We are a SaaS-based product but one of the client requirement is to make our application accessible only on their intranet. Is that even possible?
| pid has limited utility to derive information about the host's system state. Eg. low pid would indicate recent reboot, high pid a long running system (depending on the load and services). Attacker could constantly monitor your actual pid and make educated guess about uptime. Eg. predict if an important kernel security ... | I think using a pid for this is probably inappropriate. It doesn't guarantees what you are checking (because pids can wrap), and it may leak information, and it provides a path for the remote to forge pids and scan what pids are on your system.
It would be better to generate a handle (session cookie?) and keep track ... | https://security.stackexchange.com |
259,236 | [
"https://dba.stackexchange.com/questions/259236",
"https://dba.stackexchange.com",
"https://dba.stackexchange.com/users/150011/"
] | I have an <code>AlwaysOn AG</code> setup between <code>Database A</code> (primary replica) on <code>Server 1</code> and <code>Database B</code> (secondary replica) on <code>Server 2</code>.
If I force a manual failover from my primary replica on <code>Server 1</code> to the secondary replica on <code>Server 2</code> ... | <ul>
<li>Use <code>REPLACE(SearchTowns, ',', '|')</code> to change commas to pipes.</li>
<li>Put that result in, say, <code>@regexp</code>.</li>
<li>Construct, via <code>CONCAT</code> a single <code>SELECT</code> with
<pre><code>SET @sql = CONCAT('SELECT
name,
Town,
FROM userLocation where Town REGEXP "', @rege... | CREATE PROCEDURE <code>GetUsersByTown</code>(
IN <code>SearchTowns</code> LONGTEXT
)
BEGIN
SELECT
name,
Town,
FROM userLocation where FIND_IN_SET(Town,(SearchTowns))>0
END
| https://dba.stackexchange.com |
194,487 | [
"https://dba.stackexchange.com/questions/194487",
"https://dba.stackexchange.com",
"https://dba.stackexchange.com/users/140664/"
] | I have a Sharded Cluster and I am trying to access a specific member of a replica set within a shard.
When connecting to the mongos it is fine, but when using the same credentials on a member of the replica set I am unable to gain access even though my user has the role of root.
The error is:
<blockquote>
SCRAM-SH... | When you are using <code>mongoS</code> authentication is done against config servers <code>admin</code> database. When you connect directly to replica set, you are authenticating against replica set's <code>admin</code> database, where you don't have that <code>root</code> user set.
What can you do? Start replica set'... | shard members authentication requires local credentials. As what JJussi has said, you need to create local users on the sharded replica sets.
| https://dba.stackexchange.com |
349,852 | [
"https://softwareengineering.stackexchange.com/questions/349852",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/253077/"
] | So basically I have an object with a few properties in it:
<pre><code>public MyObject
{
public string Name {get;set;}
public bool Complete {get; set;}
}
List<MyObject> myList = new List<MyObject>();
myList.Add(new MyObject("Page1", true));
myList.Add(new MyObject("Page2", false));
myList.Add(new MyObject... | There is a difference between a thing and things <em>related to</em> that thing. To illustrate, consider your example:
<pre><code>public class OrderBatch{
public Customer getCustomer(){...};
public void addOrder(){...}
public void removeOrder(Order order){...}
public List<Order> getOrders(){...}
... | An order batch is a real thing. Its responsibility is keeping a bunch of order items together. That makes it a fairly complex entity that requires a lot of management tasks. So be it. As long as they make sense in the order batch context, that is just fine.
What is typically named a God class is a class that has hetro... | https://softwareengineering.stackexchange.com |
270,899 | [
"https://softwareengineering.stackexchange.com/questions/270899",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/29001/"
] | Do you have best practices regarding to which tense to use in message when you're coding exception-throwing or message-logging code: <code>"Could not acquire connection from DataSource"</code> versus <code>"Can not acquire connection from DataSource"</code>?
| I like to use present tense when the error/exception-generating code is the "root cause" of the problem, and past tense when I'm merely repackaging an error/exception from a lower layer of code.
For example, when our frontend makes a request to our backend, the backend may return an error message "Cannot connect to da... | I think past tense is a safer bet. In your example:
1) "Could not acquire connection from DataSource" - an attempt was made, failed, situation could've changed since then.
2) "Can not acquire connection from DataSource" - an attempt was made, failed, it's 100% certain that situation is still the same.
Also which ten... | https://softwareengineering.stackexchange.com |
78,686 | [
"https://dsp.stackexchange.com/questions/78686",
"https://dsp.stackexchange.com",
"https://dsp.stackexchange.com/users/59573/"
] | In other words, how can I show that if we feed an energy signal to a system whose impulse response is an energy signal, the output will also be an energy signal?
I've been trying using Rayleigh's energy theorem and Cauchy Schwarz inequality but didn't work out.
| Potentially, no.
I will attempt to find that <span class="math-container">$L_2$</span> is not closed under convolution. In other words, a convolution of two <span class="math-container">$L_2$</span> functions (or energy functions) is not necessarily in <span class="math-container">$L_2$</span>. Convolution is a complic... | Assuming by energy signal means <span class="math-container">$\int x^2(t)dt < \infty$</span> here is one way to do it.
Let's say we have
<span class="math-container">$$y(t) = x(t)*h(t)$$</span>
Convolution in time is multiplication in frequency, so we have
<span class="math-container">$$Y(\omega) = H(\omega) \cdot X... | https://dsp.stackexchange.com |
63,158 | [
"https://physics.stackexchange.com/questions/63158",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/5477/"
] | I have a good understanding of how inductors behave in electrical circuits, and a somewhat rough-and-ready understanding of how this behaviour arises from Maxwell's equations. However, what I don't have a good mental picture of is how electromagnetic induction works on the microscopic level, i.e. in terms of forces exp... | (Upgrading my comment to an answer as per @Nathanial's request but with more detail...and an animation)
Mutual induction (e.g. in a transformer) is easier to understand than self-induction (the inductance of a coil). Mutual induction separates the magnetic field source from the motion of the electrons in the pickup co... | Take a loop of wire (the simplest inductor), carrying a steady current $I_0$ (to start with). Let's say it's a superconductor, so the current is really staying constant. You understand that there is also a steady magnetic field created by this current, $B_0$.
So far, there is no force on the electrons--or at any rate,... | https://physics.stackexchange.com |
247,062 | [
"https://physics.stackexchange.com/questions/247062",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/93868/"
] | I'm just learning about radioactivity, and there's one thing I'm unclear about.
Take $\beta -$ decay, for example. Since a neutron splits into a proton and an electron (and an anti neutrino), but the electron shoots out of the atom, the product has one extra proton, and hence is not electrically neutral, right?
I ju... | Radioactivity occurs (with the exception of k-capture in which the nucleus captures an orbiting electron) inside the nucleus of atoms, not in the electron shells. Yes, the product has one extra proton, and thus is now a different element, jumping up one in the Periodic Table. No nucleus is electrically neutral. Whether... | Radioactive materials are studied in bulk matter. The electron that left with beta decay will become part of the conduction band electrons for the lattice the atom is in, and another electron will be drawn in very fast from the conduction band.. To remain an ion the atom should be isolated from bulk matter, and usual... | https://physics.stackexchange.com |
330,420 | [
"https://softwareengineering.stackexchange.com/questions/330420",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/164782/"
] | I have an api with 3 layers
1.) The endpoint layer which exposes api endpoint handler functions. These generally call the business layer, aggregate the results to form an http response.
2.) The business logic layer, which provides interfaces to get or edit data while employing business rules behind the scenes, modify... | If there is only one acceptable order, business wise, decide if this ordering is an actual business rule, or is it something inherent to the data itself.
For instance:
<ul>
<li>A table of persons may be sorted by first or last name, or a phone number, or an e-mail address. Maybe business rules in a specific domain di... | If you're consistently sorting data sets the same way and they're not too large, you can do it in the database. Databases are pretty competent at sorting especially when they can utilize an index.
At some point, the sorting is too much of a performance hit. That's a good time to move it to your application. For apps ... | https://softwareengineering.stackexchange.com |
157,380 | [
"https://security.stackexchange.com/questions/157380",
"https://security.stackexchange.com",
"https://security.stackexchange.com/users/145755/"
] | Like a lot of people, I use a password manager (Keypass). For convenience I have this stored on Dropbox and is a part of the various backups that I do (Both local and offsite).
I am thinking of storing sensitive documents in this file (i.e. Passport, Drivers License etc) for convenience and [physical] safety but I am ... | Keepass uses state of the art encryption and is considered safe now. The same holds true for alternatives for encrypting files in a public cloud drive, like a Veracrypt container or a stacked filesystem (like gocryptfs or cryptomator).
But (there is always a "but"), if you put anything encrypted into someone else's ha... | No, it's not a good idea.
Make a small encrypted container (like Veracrypt volume) and store them there.
It's easy to use and you only need to remember one password to access that volume.
| https://security.stackexchange.com |
577,066 | [
"https://physics.stackexchange.com/questions/577066",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/273689/"
] | How is coefficient of static friction and coefficient of kinetic friction is calculated in real life without knowing the frictional force?
| I can not give you an example for all surfaces, but for an inclined plane, the formula is pretty straightforward. Suppose you wanted to find the coefficient of friction between a block and an incline. Keep the block on the incline, and if the block is stationary, try to increase the angle of incline until the block jus... | <strong>Static coefficient</strong>
I simple experiment would consist of taking a ramp of material <span class="math-container">$A$</span> and a block of material <span class="math-container">$B$</span>. Let the ramp start completely horizontal and start lifting the ramp gradually. As soon as the the block starts slidi... | https://physics.stackexchange.com |
131,067 | [
"https://electronics.stackexchange.com/questions/131067",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/40929/"
] | <strong>Question</strong>
The voltage waveform measured at the 50ohm antenna terminal of a 11750-kHz AM (DSB-LC) short-wave broadcasting transmitter is shown in Fig. Q3.
<img src="https://i.stack.imgur.com/QsX4U.png" alt="enter image description here">
How to draw the one-sided magnitude spectrum of the transmitted ... | You're forgetting a couple of important facts:
<ol>
<li>A flip-flop isn't a single atomic gate, but made up of multiple gates.</li>
<li>It takes time for a signal to pass through a gate (or <em>propagate</em>).</li>
<li>There is no such thing as a pure square wave.</li>
</ol>
Take this diagram of a transparent latch:
<... | Timing analysis of a logic system depends on having well bounded delays from the clock pin to the output (Q, Qb) pins of the latches and flops. In order to bound the upper limit on the clock to Q delay time, we also have to bound the setup and hold time for data being stable relative to the clock.
Flip flops and latc... | https://electronics.stackexchange.com |
452,180 | [
"https://electronics.stackexchange.com/questions/452180",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/228390/"
] | When doing rtl design, mux is always used to select the input of a block/module, for example:
<pre><code>input [135:0] dataA, dataB;
assign FIFO_DATAIN=(sl)?dataA:dataB;
myfifo xxx(.(FIFO_DATAIN)
.... );
</code></pre>
Since the input data is 136 bits wide, this may lead to timing violations and requires a lo... | It really doesn't matter how you write the code, it will be synthesized to the same thing. A 136 bit 2:1 mux is really not that bad. It's really the number of inputs that really dictates the complexity and causes timing issues, not so much the width, though that does place a large fanout on the select signal. If that w... | I don't think it matters. Synthesis will smash this down to 136 2:1 muxes regardless of how you describe them in HDL. That's not that much in the larger scheme of things if you're building something with that large of a datapath (128 data, 8 enables, right?)
Insert register slices if it needs help to close timing.
| https://electronics.stackexchange.com |
164,264 | [
"https://electronics.stackexchange.com/questions/164264",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/54246/"
] | If the positive input of an operational amplifier is grounded, the negative input is said to be virtually grounded and it has therefore zero potential.
But the contrary is not true. A grounded negative input doesn't make the positive input virtually grounded.
Why?
| For your answer, you have to go back to basic op-amp theory.
When you provide negative feedback to an op-amp, you make the negative input track the positive input as closely as possible.
Now tie the positive input to ground. The op-amp feedback is going to try to keep the negative input at that same potential: gro... | It's negative feedback and high open loop gain that creates a virtual ground. You don't get negative feedback to the non inverting input of any differential amplifier; you get positive feedback and this does not create a virtual ground.
You can add an inverting amplifier after a differential amplifier and this, in eff... | https://electronics.stackexchange.com |
243,677 | [
"https://security.stackexchange.com/questions/243677",
"https://security.stackexchange.com",
"https://security.stackexchange.com/users/249571/"
] | A simple question which I cannot find any guidance on the RFC6749 (or related) spec.
I have an eCommerce public client (SPA & mobile), where I want to postpone as much as possible the authentication process (possibly registration too for new customers). I will only ask the customer at the end of his purchase journe... | <blockquote>
would this be more difficult to crack or impossible?
</blockquote>
If you use a modern encryption method like AES256 properly it is already effectively impossible to decrypt.
You can learn about AES256 from a variety of sources including cryptography textbooks, which are perhaps a good place to start for a... | While it is possible to gain an improvement in security by encrypting data with multiple algorithms in this way, it's generally not needed and not a good idea.
<ul>
<li>If you are using a secure 256-bit AEAD algorithm with a securely generated key and nonce (that is, using a KDF or both randomly generated on each use),... | https://security.stackexchange.com |
422,011 | [
"https://physics.stackexchange.com/questions/422011",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/182971/"
] | How dose the factor $1/2$ in $E=\frac{1}{2} mv^2$ disappear in QM?
The TDSE writes:
$$
H |\psi \rangle = i\hbar \frac{d}{dt}|\psi \rangle
$$
The momentum operator is defined as:
$$
\langle x|p|\psi \rangle=-i\hbar\frac{d\psi}{dx}
$$
Comparing the two operators, we can see that $p$ does have the dimension of Energy dev... | Excellent question. The first equation encodes Einstein's relation $E= hf$ and the second encodes de Broglie's relation $p=h/\lambda$. Your paradox can be phrased as the surprise that $E/p = f\lambda$ which is an expression for a plane wave’s velocity $c$, but that in classical mechanics a free particle has energy $E=p... | $H=\frac{p^2}{2m}$ <- there it is.
| https://physics.stackexchange.com |
4,493,472 | [
"https://math.stackexchange.com/questions/4493472",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/17341/"
] | it is always true that ?
<span class="math-container">$$ \int _{a}^{b} f(x)dx > \sum_{n=a}^{b}f(n) $$</span>
where a and b are integers. Providing the funcion is always increasing/decreasing <span class="math-container">$ f'(x) >0 $</span> or <span class="math-container">$f'(x)<0)$</span> on the nterval <span... | if we have <span class="math-container">$f(x) > 0$</span> and <span class="math-container">$f'(x) > 0,$</span> then
<span class="math-container">$$ \int_{a-1}^{b} \; f(x) \; dx \; < \; \sum_{j=a}^b \; f(j) \; < \; \int_{a}^{b+1} \; f(x) \; dx $$</span>
if we have <span class="math-container">$f(x) &g... | Is not always true.
Take <span class="math-container">$f(x) = x$</span>, and <span class="math-container">$a = 0, b = 1$</span>.
Then <span class="math-container">$\int_{0}^{1}x dx = \dfrac{x^{2}}{2} \Bigg|_{0}^{1} = \dfrac{1}{2} < 1 = 1 + 0 = \sum_{n=0}^{1} n$</span>
| https://math.stackexchange.com |
99,239 | [
"https://mathoverflow.net/questions/99239",
"https://mathoverflow.net",
"https://mathoverflow.net/users/24340/"
] | Suppose $\mathcal{H}$ is a separable Hilbert space over $\mathbb{C}$ (countable dimensions) with inner product $\langle,\rangle$. Let $A$ be a bounded linear operator on $\mathcal{H}$, i.e, in $B(\mathcal{H}$). Suppose further that $A$ is not a multiple of the identity
operator. Then is it true that there exist two ... | The answer is yes, this is true (assuming that the Hilbert space is complex).
If $\langle \xi,A\xi \rangle = \sigma$ for some $\sigma \in \mathbb C$ and all $\xi$, then $B:=A - \bar \sigma 1_H$ has the property that $\langle \xi,B\xi \rangle =0$ for all $\xi \in H$. We need to show $B=0$. Let $\xi \in H$ be arbitrary ... | Nothing new compared to Andreas's answer, just wanted to stress the polarization idea:
<strong>Notation</strong>: For $H$ a Hilbert space, and $A\in B(H)$ (bounded linear operator), write $q_A$ for the quadratic form $x\mapsto \langle Ax,x\rangle$.
<strong>Lemma</strong> ('polarization'): If $H$ is a complex Hilbert... | https://mathoverflow.net |
447,464 | [
"https://stats.stackexchange.com/questions/447464",
"https://stats.stackexchange.com",
"https://stats.stackexchange.com/users/209434/"
] | Under the condition of simple linear regression model ( <span class="math-container">$Y_i = \beta_0 + \beta_1X_i + \epsilon_i$</span>) ordinary linear estimators(<span class="math-container">$\hat{\beta_0}$</span> and <span class="math-container">$\hat{\beta_1}$</span>) have minimum variance among all linear estimators... | <code>proportions_ztest</code> seems to work exactly as documented.
Unfortunately what the documentation says it does is just not what you're expecting it to do.
By default this function uses the <em>sample</em> proportion in calculating the standard error of <span class="math-container">$p-p_0$</span>. There's an o... | Even though @Glen_b answer is completely right, it doesn't mention the parameter they are referring to.
For others who may fall into this same problem, the right way of using <code>proportions_ztest</code> the way the OP tried to use it is as follows:
<pre><code>from statsmodels.stats.proportion import proportions_ztes... | https://stats.stackexchange.com |
978,072 | [
"https://math.stackexchange.com/questions/978072",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/185069/"
] | Without using the truth table, I need to prove:
$$\big((p\rightarrow q) \lor (p \rightarrow r)\big) \rightarrow (q\lor r)\equiv p \lor r \lor q$$
Up until now, we've been using truth-tables to verify equivalences. So I'm a bit lost on where to begin without using a truth-table.
| $$\begin{align}\big((p\rightarrow q) \lor (p \rightarrow r)\big) \rightarrow (q\lor r) &\equiv \lnot\big((\lnot p \lor q) \lor (\lnot p \lor r)\big) \lor (q \lor r)\tag{1}\\ \\
&\equiv \big(\lnot(\lnot p \lor q) \land \lnot (\lnot p \lor r)\big) \lor (q\lor r)\tag{2}\\ \\
&\equiv \big((p \land\lnot q)\la... | A solution using just words and definitions of the connectives:
Let $$ \alpha = \big((p\rightarrow q) \lor (p \rightarrow r)\big) \rightarrow (q\lor r), \;\;\;\; \beta = p \lor q \lor r$$
Suppose $\alpha $ is true. Then either $ \big((p\rightarrow q) \lor (p \rightarrow r)\big) $ is false, or $ \big((p\rightarrow q)... | https://math.stackexchange.com |
72,471 | [
"https://math.stackexchange.com/questions/72471",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/17616/"
] | There's a matches riddle that I can't quite solve.
Given the following layout (a 4 matches plus sign connected to a 8 matches square):
<pre>
__|__
__|__
| |
|__ __|
</pre>
I need to transform this into <strong>exactly</strong> 3 squares by moving 5 matches only.
It's driving me crazy, so if you know how to solv... | <pre>
__|__
|__ __
| |
|__ __|
</pre>
<pre>
__|__
|__ __
| __|
__ __|
</pre>
<pre>
__|__
|__ __
| __|
|__|
</pre>
<pre>
__|__
|__|__
__|
|__|
</pre>
<pre>
__
__|__
|__|
__|
|__|
</pre>
<pre>
__
|__|__
|__|
__
|__|
</pre>
Or do you mean?
<pr... | By moving only three matches (the right hand of the plus sign and the two parallel matches below it), you can write a $4$, a $0$ and a $1$ : you get your three squares and you economize two moves !
| https://math.stackexchange.com |
308,325 | [
"https://mathoverflow.net/questions/308325",
"https://mathoverflow.net",
"https://mathoverflow.net/users/11546/"
] | There are two "opposite" functors:
$$ op_\Delta\colon sSet\to sSet$$
and
$$op_s\colon sCat\to sCat.$$
The first takes a simplicial set to its opposite simplicial set by precomposing with the opposite of a functor $\Delta\to \Delta$ which is the identity on objects and takes a morphism $\langle k_0,\ldots,k_n\rangle\co... | It all follows from the following elementary lemma:
$\mathfrak{C}([n]^{op})$ is isomorphic to $\mathfrak{C}([n])^{op}$ as a cosimplicial simplicial category (in fact, they are actually equal, since the components of the natural isomorphism are all identities).
proof: It is an immediate calculation from the definit... | (This is a supplement to Harry's answer which doesn't quite fit into a comment.)
As Harry mentions, it suffices to show that the cosimplicial objects <span class="math-container">$\mathfrak{C}((\Delta^\bullet)^\mathrm{op})$</span> and <span class="math-container">$(\mathfrak{C}(\Delta^\bullet))^\mathrm{op}$</span> are ... | https://mathoverflow.net |
697,145 | [
"https://physics.stackexchange.com/questions/697145",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/281576/"
] | Imagine two cars (A and B) of mass <span class="math-container">$m$</span> that want to destroy themselves by colliding. They need a velocity of magnitude <span class="math-container">$2v$</span> with respect to each other to achieve the destruction that they want and they have a fixed amount of gasoline that they can ... | I wanted to add a slightly different perspective to the other (correct and good) answers.
Kinetic energy is not invariant under a change of frame. Imagine a box of mass <span class="math-container">$m$</span> at rest. If I boost into a frame moving at velocity <span class="math-container">$V$</span>, the kinetic energy... | <blockquote>
My question is: how can it be possible for the same event to happen using only half the energy?
</blockquote>
Well, you are neglecting momentum, so you are also neglecting half of the energy in the first scenario.
Let's assume that the collision is perfectly plastic. With <span class="math-container">$E=\f... | https://physics.stackexchange.com |
1,879,296 | [
"https://math.stackexchange.com/questions/1879296",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/352447/"
] | Consider the sequence $(a_n)_{n \geq1}$ such that $a_0=2$ and $a_{n-1}-a_n=\frac{n}{(n+1)!}$. Evaluate $$\lim_{n \to \infty} ((n+1)!\ln (a_n))$$
Could someone hint me as how to achieve value of $a_n$ from given information.
| <strong>Hint</strong>. The key word is telescoping sums,
$$
a_{n-1}-a_n=\frac{n}{(n+1)!} \implies a_0-a_n=\sum_{k=1}^n\frac{k}{(k+1)!}
$$ and
$$
a_0-a_n=\sum_{k=1}^n\frac{(k+1)-1}{(k+1)!}=\sum_{k=1}^n\frac1{k!}-\sum_{k=1}^n\frac1{(k+1)!}=1-\frac1{(n+1)!}
$$
Can you take it from here?
| Hint: Show by induction that $a_n=1+\frac{1}{(n+1)!}$
| https://math.stackexchange.com |
70,597 | [
"https://security.stackexchange.com/questions/70597",
"https://security.stackexchange.com",
"https://security.stackexchange.com/users/58556/"
] | Once I forget my ID's password. I recovered it and changed it about a month ago but I forget again.
Is there any way to see the details stored in laptop what i typed in past to till now from my keyboard of laptop without using a keylogger?
| No, they can only see the encrypted traffic flowing from yourself to Google's servers. They cannot see the actual content of the traffic (your emails).
However, if your ISP forces you through a web proxy and makes you use their certificate, they could then see the content of your traffic. I would be cautious if you ... | <h1>In a Nutshell</h1>
<strong>Yes</strong>, your ISP and government can read your emails, even when using encryption because of a number of vulnerabilities, and the fact that most emails are not encrypted on email provider's servers.
<h1>Definitely Not in a Nutshell</h1>
Your ISP can employ a number of tactics to r... | https://security.stackexchange.com |
164,039 | [
"https://electronics.stackexchange.com/questions/164039",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/71316/"
] | I understand how a basic comparator op amp works and how a capacitor charges individually, but I can't seem to put it all together to make this circuit. I think I might be messing up with the voltage rails and grounds somehow. The point of the circuit is for the LEDs to light up at ~2 second intervals. The output of th... | Figured it out, I kept trying to use these 'DC rail' components and was failing and getting errors I didn't understand. I switched to just basic DC sources and got it to work. Thanks for the suggestions, they got me thinking. Here's the circuit for anyone in the future who might be looking:
<img src="https://i.stack.i... | <blockquote>
The output of the comparator is supposed to transition from -13V to
12V where Vcc is +-15V.
</blockquote>
You may easily have damaged your LEDs. When the comparator is supposedly not driving a LED you will have generated -13V to ground across it (and its series resistor).
Most LEDs have a maximum rev... | https://electronics.stackexchange.com |
728,364 | [
"https://physics.stackexchange.com/questions/728364",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/346094/"
] | I encountered a question that entails a bullet being shot at a pendulum sand bag that causes it to swing. One part of the question asks if the collision is elastic or inelastic. Would I say its inelastic since realistically energy would be lost even though I used the conservation of momentum and energy formulas to get ... | The collision is inelastic. Not because of non-idealities imposed by the real world, but because even on paper the collision is inelastic. If the problem is what I am imagining, after the collision the bullet is lodged in the sand. Any time two colliding objects stick together, (mechanical) energy is not conserved.
The... | In many problems in mechanics, bodies are considered rigid bodies and as such can have no change in internal energy. Examples include rigid bodies sliding with slipping down an incline, and elastic collisions between two rigid bodies.
In reality, no body is rigid but for certain situations this is a reasonable assumpt... | https://physics.stackexchange.com |
28,711 | [
"https://dba.stackexchange.com/questions/28711",
"https://dba.stackexchange.com",
"https://dba.stackexchange.com/users/11154/"
] | What I'm trying to do is backup one of our production databases and restore them as our dev database (overwriting what's been there).
That's how I back up:
<pre><code>backup database [authfx] to disk = N'f:\db_backups\authfx\authfx-latest.bak'
with
noformat,
init,
name = N'authfx Latest Full Database... | Unfortunately not. SQL Server will always attempt to restore to <strong>exactly</strong> what is recorded in the backup file, unless you explicitly specify otherwise (with <code>MOVE</code> in this case).
The <code>REPLACE</code> option only works if you're replacing files owned by the database you're restoring (whic... | <code>RESTORE DATABASE DB_NAME ... WITH RECOVERY, REPLACE;</code>
-- will restore your "DB"(overwrite) ALWAYS!
Do not listen for "DB_A & DB_B as well". "DB" will be your restored database name.
Use RECOVERY for the state "ON-LINE" and REPLACE for overwriting existing database files.
Use MOVE for the different fil... | https://dba.stackexchange.com |
73,671 | [
"https://datascience.stackexchange.com/questions/73671",
"https://datascience.stackexchange.com",
"https://datascience.stackexchange.com/users/96529/"
] | I've started reading some literature about reinforcement learning and I can't understand what is the result of the application of RL. I'll be more specific: let's have a time series problem in continuous state space, finite numbers of actions, and a linear approximator of the policy function. So I follow an algorithm t... | So there are a few things you seem to be confused about. Short answer is no.
In Reinforcement Learning (RL), the goal is to learn a policy for taking actions in a Markov Decision Process (MDP) to maximize a reward. If your problem can be described as a Markov Decision Process, then RL may be a good solution. Theoretica... | Is the result of RL is a classic function to (re)apply at each time step?<br>
In some manner yes, when using RL to find the best policy you end up with a policy that can be described as a function(classic or not) from possible states to possible actions.
As if it was a regression?<br>
No, regression algorithms 'solv... | https://datascience.stackexchange.com |
78,061 | [
"https://mechanics.stackexchange.com/questions/78061",
"https://mechanics.stackexchange.com",
"https://mechanics.stackexchange.com/users/58704/"
] | My fixd scanner only says low voltage. How can I increase the volts at OBD connection my check engine light is on trying to get code.
1999 GMC Sierra 2500 with a 5.3 litre Vortec engine
Scanner works on my other vehicle.
| Add a short length of 2X4 or 4X4 to the lifting pad on the floor jack. Do not use brick as they can break. I have a 4X4 with a groove cut in it to fit the lifting point of a particular car .
| There are several alternative jacks.
A so called uni-jack is a combo jack stand and hydraulic jac k.(<$100 USD)
There are floor jacks with raised saddles, where the saddle assembly is an extended rod, with a saddle at he top. You still have similar lift, but it is offset upwards by the metal extension. (<$100 US... | https://mechanics.stackexchange.com |
19,339 | [
"https://mathoverflow.net/questions/19339",
"https://mathoverflow.net",
"https://mathoverflow.net/users/184/"
] | I think I am confused about some terminology in algebraic geometry, specifically the meaning of the term "torsor". Suppose that I fix a scheme S. I want to work with torsors over S. Let $\mu$ be a sheaf of abelian groups over S. Then my understanding is that a $\mu$-torsor, what ever that is, should be classified by th... | As remarked by Brian Conrad above, there is an excellent explanation of all this in Milne's book <em>Étale cohomology</em>, Section III.4. There wouldn't be much point in reproducing the details here, but the main issues are:
<ul>
<li>You need to decide whether a torsor is going to be a scheme over <em>S</em> which l... | So thanks to the comments of Tyler Lawson I have been able to figure out what is happening in this example, so I thought I should post it as an answer. I think this is also what Torsten Ekedahl was getting at in his comment, as well.
I think it helps to be extra clear because this example is rather confusing. For sta... | https://mathoverflow.net |
2,642,332 | [
"https://math.stackexchange.com/questions/2642332",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/506839/"
] | For every $n\in \Bbb N$, let $g_{n}:A\mapsto \Bbb C$, where $A\subseteq \Bbb C$. prove from the definition of pointwise convergence, that if the sequence $(g_{n})$ converges pointwise to a function $g:A\mapsto \Bbb C$ then $g$ is unique.
Here is my attempt, if anyone could tell me if its correct, or any detail is miss... | This is mostly correct but there is some confusion about where you are evaluating your functions. What does $|g-f|$ mean? What is this "$x$" you are plugging into some but all of your functions?
To make sense of this, you need to <em>choose</em> some specific $x$ and use it consistently. If $f\neq g$, that means th... | We have $g(x)=\lim_n g_n(x)$, $(\forall)x\in A$, by definition. The limit of a sequence of complex numbers is unique (if it exists). Therfore, $g$ is uniquely defined.
| https://math.stackexchange.com |
49,278 | [
"https://mathoverflow.net/questions/49278",
"https://mathoverflow.net",
"https://mathoverflow.net/users/370/"
] | For a connected reductive algebraic group $G$ over a field $k$, other than the \'etale fundamental group of $G$ (regarded just as a scheme), there seems to be another notion, usually called the algebraic fundamental group of $G.$ I am not sure of its definition, but I guess (at least when $G$ is split) it might be some... | At Jim's request, here's an expanded version of my comments above. I will have to use some facts from the topological theory of complex algebraic varieties, but out of stubbornness I will not use any such facts which are part of the theory of Lie groups (the maximal compact subgroup, facts specific to complex semisimp... | One reference: The section "The algebraic fundamental group of a reductive group", in "Abelian Galois Cohomology of Reductive Groups", by Mikhail Borovoi. This has exactly what you're looking for, I think.
| https://mathoverflow.net |
294,349 | [
"https://softwareengineering.stackexchange.com/questions/294349",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/192837/"
] | I have been working on a project in JavaScript which requires a data structure (read only), to be shared between two functions.
<pre><code>var mySharedData = ['hours', 'minutes', 'seconds'];
</code></pre>
Now I have two functions that need access to this (static) read only data structure.
<pre><code>var sampleFuncti... | If <code>mySharedData</code> is private for both closures:
<pre><code>(function (context) {
var mySharedData = ['hours', 'minutes', 'seconds'];
context.sampleFunction1 = function (userSuppliedData) {
//map over user data applying mySharedData to it
// mySharedData....
};
context.sampl... | Use it any way you want.
Using an immutable constant from two functions is not in any way problematic or impure.
A problem arises if one of the functions mutates the value. In JS this can be prevented by declaring the binding with <code>const</code> and by using <code>Object.freeze</code> to make the value immutable.... | https://softwareengineering.stackexchange.com |
140,673 | [
"https://stats.stackexchange.com/questions/140673",
"https://stats.stackexchange.com",
"https://stats.stackexchange.com/users/45224/"
] | My raw data consists of a 60-day time series with a downward trend. The data is weekly so the frequency is set to 7.
<img src="https://i.stack.imgur.com/lX28r.png" alt="Time Series">
I calculated the difference of the data which looks like this
<img src="https://i.stack.imgur.com/QQiXr.png" alt="Difference">
When I ... | In R <code>acf</code> starts with lag 0, that is the correlation of a value with itself. <code>pacf</code> starts at lag 1.
Just a peculiarity of her R implementation. You can use the <code>Acf</code> function of the package <code>forecast</code> which does not show the lag 0 if that bothers you.
| The putative contradiction is based on the different lag-representation for PACF- and ACF- plots in R: ACF starts at lag 0 and PACF starts at lag 1.
In principal, PACF and ACF at lag 1 should be equal. The theoretical ACF for a stationary time series $Y_t$ is just the autocorrelation, so $ACF(1)= Corr(Y_t,Y_{t-1})$.
... | https://stats.stackexchange.com |
137,757 | [
"https://mathoverflow.net/questions/137757",
"https://mathoverflow.net",
"https://mathoverflow.net/users/37709/"
] | Let $X$ be a smooth projective complex algebraic variety of general type. Suppose that the (topological) fundamental group of $X$ is an infinite abelian group and that $\pi_2(X^{an})$ is finite.
What can we say about $X$?
I am mainly interested in the case where $\dim X = 2$, and $\Omega^1_X$ satisfies some positivit... | I combine user37314's answer and my comments; the claim is that any smooth projective complex algebraic surface with $\pi_1$ abelian and $\pi_2$ finite has a finite cover which must be an abelian surface; in particular, $X$ cannot be of general type.
By replacing $X$ by a finite cover, we may assume that $\pi_1(X)$ is... | Your assumption implies that there is a finite holomorphic map of the universal cover of X into complex euclidean space .In particular the universal cover is Stein.
| https://mathoverflow.net |
28,651 | [
"https://softwareengineering.stackexchange.com/questions/28651",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/11193/"
] | I decided to learn programming. I've been reading SO for few days, and I think I will start with C++, as I read some articles. I am aware of loops, arrays, program logic and objects a little and I need someone to look me over and help me with small questions I get when doing my first projects.
So here is the question... | Joining an open-source project is certainly one way to get started. However, I've been using open-source software for years, and quite frankly, the quality on almost all such projects is generally in the toilet. If you learn your programming and design skills entirely from them, you'll probably pick up some very poor o... | To find a mentor, don't look for a mentor. Try to improve yourself in specific ways. If you work hard enough at getting better, you will both find that you come in contact with like-minded folks, and find that you have something in common with those people.
Users groups are the likely place to find a mentor, but no ... | https://softwareengineering.stackexchange.com |
621 | [
"https://chemistry.stackexchange.com/questions/621",
"https://chemistry.stackexchange.com",
"https://chemistry.stackexchange.com/users/74/"
] | Is it possible (advisable?) to make a sealed tube by melting and twisting the end of a borosilicate test tube? One issue that I can think of is that the pressure might be too high if I then proceed to heat the tube. I thought that I could maybe connect the tube to a vacuum tube and heat it in the middle. Any experience... | Usual way to work with air sensitive compounds is to work on Schlenk-line (search Wiki). When you transfer your substance you can leave it in Schlenk tube, or if it's really sensitive and you need to keep out of the line for longer period of time you have in general three possibilities: (1) use glassware with J. Young ... | Possible? Doubtless. Advisable? Depends what you're sealing, I'm sure. The pressure won't be a problem though, if anything it'll be a partial vacuum inside and you'd have to heat it near the tube's melting point to get it back to atmospheric pressure. Consider that as you're heating the tube to seal it, you'll heat a ... | https://chemistry.stackexchange.com |
4,000,009 | [
"https://math.stackexchange.com/questions/4000009",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/773147/"
] | <strong>Synopsis</strong>
In Tao's <em>Analysis 1</em>, we are asked the following:
<blockquote>
Let <span class="math-container">$\alpha$</span> be a real number, and let <span class="math-container">$f:(0,\infty) \to \mathbb{R}$</span>
be the function <span class="math-container">$f(x) = x^{\alpha}$</span>. Show that... | If you break the problem into approaching from the right and the left of 1, then the inequalities will be more clear I think.
Note that for <span class="math-container">$x>1$</span> <span class="math-container">$\frac{x^{\alpha}-1}{x-1}$</span> is increasing in the <span class="math-container">$\alpha$</span> variab... | It sounds like they want you to prove it for the integers, then the rationals, then the real numbers.
If <span class="math-container">$\alpha$</span> is a positive integer <span class="math-container">$x^\alpha - 1 = (x-1)(x^{\alpha-1} + x^{\alpha-2} + \cdots + 1)$</span>
<span class="math-container">$\lim_\limits{x\to... | https://math.stackexchange.com |
173,991 | [
"https://physics.stackexchange.com/questions/173991",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/68648/"
] | I have stucked with finding max height of an $m$, given only $m, M$ and initial velocity of $m$ - $\vec{V}$. There is no friction in the system. As I understood I need to find $\vec{V_0}$ - velocity of $m$ after it passed the radius, after that it is easy. But to find out $\vec{V_0}$, I need to calculate which amount o... | Using momentum conservation in the $x$ direction we get:
$mv=(M+m)u$
Where $u$ is the velocity of the two masses at the maximum height of $m$.
Also the energy conservation implies that:
$\frac{1}{2}mv^{2}=\frac{1}{2}Mu^{2}+\frac{1}{2}mu^{2}+mgH_{max}$
Where $mgH_{max}$ is the potential energy of $m$ at the maximum... | To answer this question you need to take advantage of two principles:<br>
The conservation of energy<br>
The conservation of linear momentum
When using the conservation of energy, we need to know the kinetic energy the larger block attains in the end as one of the terms. That's why we need to use the conservation ... | https://physics.stackexchange.com |
3,688,277 | [
"https://math.stackexchange.com/questions/3688277",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/784628/"
] | Let <span class="math-container">$(\Omega,\mathcal{F},\mathcal{F}_{\cdot}=(\mathcal{F}_k)_{k\in\mathbb{N_0}},\mathbb{P})$</span> be a filtered probability space and <span class="math-container">$\sigma,\tau:\Omega\to\mathbb{N}\cup\{\infty\}$</span> two <span class="math-container">$\mathcal{F}_{\cdot}$</span>-stopping ... | For the other inclusion, suppose that <span class="math-container">$A \cap \{ \tau \wedge \sigma \leq t\}$</span> is in <span class="math-container">$\mathcal{F}_t$</span>. You want to prove that <span class="math-container">$A \cap \{ \tau \leq t \}$</span> is also in <span class="math-container">$\mathcal{F}_t$</span... | Note that <span class="math-container">$\tau \wedge \sigma \leq \tau$</span> and <span class="math-container">$\tau \wedge \sigma \leq \sigma$</span> (with probability one). It follows that
<span class="math-container">$$\{\tau \leq k\} \subseteq \{\tau \wedge \sigma \leq k\} \text{ and } \{\sigma \leq k\} \subseteq \{... | https://math.stackexchange.com |
30,968 | [
"https://physics.stackexchange.com/questions/30968",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/10155/"
] | <ol>
<li>I heard somewhere that the second law of thermodynamics is stating that some heat (energy) becomes unusable for work (at the scale of the whole universe). Why is it like that? Can't heat be converted into some energy forms? I do understand that entropy is the measure of spontaneity, but I am having hard time u... | Actually heat is indeed usable as you state, but we should understand what it really means.
Heat is a way in which energy is transfered from one system to another. The other way is work. When we say that we use heat to produce work, we are making a conversion from one of these energy forms to the other. To do that, a ... | There's an analogy based on viewing heat as a liquid e.g. water. You need to be a bit cautious with this as like all analogies it fails if pushed too far, but I think it helps with your question.
Anyhow, if heat is like water then temperature is like water pressure. If you have water at different pressures you can use... | https://physics.stackexchange.com |
9,541 | [
"https://mechanics.stackexchange.com/questions/9541",
"https://mechanics.stackexchange.com",
"https://mechanics.stackexchange.com/users/4908/"
] | Most of the time when I brake at low speeds I hear a clicking type sound, that is fairly faint. I do NOT hear squeaking, grinding or any high pitched noises that might indicate my brake pads are wearing down, or anything that sounds really bad. I also do NOT feel anything in the pedal with the clicking/tapping. It seem... | It turns out that the brake pads were improperly installed. Furthermore, the problem seemed to occur far more often when the breaks were wet. I'm not sure if that caused the pads to "slip" more or what.
| I would look at the springs, shims and clips that hold the pads in place. It is possible that one of the springs has weakened or rusted. When the brakes are applied the pad shifts resulting in the click. If you remove the pads you may detect a shiny spot on one or more of the "ears" of the pad.
| https://mechanics.stackexchange.com |
42,079 | [
"https://softwareengineering.stackexchange.com/questions/42079",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/4091/"
] | I recently observed some contract offers which included a "code review by third party" clause - the contract would not pay out fully until the code review was completed and it received a pass.
I was surprised, especially considering that these were fairly simple, and small-scale contracts (churning out vanity apps for... | It depends what you agreed to provide.
If you provide an <strong>outcome</strong>, then it is perfectly normal. By cons, if you provide <strong>means</strong> (typical case), it is not acceptable.
The company that use that clause may have been is some difficult situations where she had invested some money in a develo... | No. Code Reviews of Contractors should be done by their peers and not by some 3rd Party as they might not be aware of problem domain.
| https://softwareengineering.stackexchange.com |
514,834 | [
"https://physics.stackexchange.com/questions/514834",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/247684/"
] | I have just started to study the electromagnetic waves as a personal interest. I wonder if there exist a much higher frequency of electromagnetic wave than Gamma Ray's which can even penetrate Earth. With our current measuring apparatus, is it possible to measure such high frequency waves if they penetrate everything?
... | For an electro-magnetic wave, the ability to penetrate matter goes as <span class="math-container">$1/{\sqrt{f}}$</span>.
So as you increase the frequency, the penetration gets worse. By the time you get to gamma-rays, the energy is so high that the "rays" (at this point you're better thinking of them as particles - p... | There are waves called <em>Cosmic Radiation</em> that have a much higher frequency than Gamma Rays do. Some scientists also think that some Ultraviolet waves can have a higher frequency than Gamma Rays, but not bigger than Cosmic Radiation.
| https://physics.stackexchange.com |
172,334 | [
"https://electronics.stackexchange.com/questions/172334",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/77303/"
] | Most of the devices to measure current at micro amps level or lower recommend a input resistance of more than 1kOhms.
(As for an example , shorting the ammeter leads, which is essentially what happens on connecting the low resistance source, produces noise in 0.5 mA range)
How do we measure current from sources which ... | The following algorithm will do what you want:
<pre><code>period = 256;
on_time = 34; // Or whatever you want
off_time = period-on_time;
count = 0;
while (1);
{
if (count >= 0) {
count -= off_time;
output_high();
} else {
count += on_time;
output_low();
}
wait_for_nex... | Sounds like you want a delta-sigma modulator instead of 'regular' PWM. A delta-sigma modulator emits a pulse density modulated output, moving the noise mostly to high frequencies so it is easier to filter out. Generally this is done with dedicated hardware to get a very high output rate, though I suppose there is no ... | https://electronics.stackexchange.com |
230,582 | [
"https://softwareengineering.stackexchange.com/questions/230582",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/114420/"
] | Most probably my boss didn't write a single word on a keyboard in his entire life.
He saw computers and he has a cell phone. He is a smart man.
<strong>How can I explain to him what a 'virtual machine' is?</strong>
(VM as in VMWare + virtual Box, not the VM as in Java, LLVM, .NET)
One of the reasons for asking thi... | Well, that depends on why you want to explain it, and in how much details.
A good first attempt could be
<blockquote>
A program to simulate a computer inside a computer. It is useful for
testing programs that need a separate computer, without actually
having a second computer.
</blockquote>
Then, you can refin... | There are three possible ways. You may need to use all of them.
<h3>By definition.</h3>
<ul>
<li>"A virtual machine is a program that simulates a physical computer." </li>
</ul>
<h3>By example</h3>
<ul>
<li>A VM is kind of like those Emulators that let you play old NES games on your current PC.</li>
<li>Smartphon... | https://softwareengineering.stackexchange.com |
664,783 | [
"https://physics.stackexchange.com/questions/664783",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/245099/"
] | Picture a light wave orthogonal to and just above the event horizon of a black hole, fired directly away from the black hole.
If the black hole is of sufficient mass, the light would be pulled back towards the black hole and would eventually reverse directions.
My two questions are:
<ol>
<li>Is this assumption correct?... | <blockquote>
If the black hole is of sufficient mass, the light would be pulled back towards the black hole
</blockquote>
If the light was emitted from <em>outside</em> the event horizon, then the black hole is necessarily not of sufficient mass. Once the photon is emitted, it moves at the local speed of light. It is... | No, your assumption is wrong.
All vanilla black holes (no charge, no spin) have an event horizon. If you are outside the event horizon, you are far enough away that light pointed directly away can escape to infinity. As in all gravitational wells, it will be red shifted. The light that reaches infinity will be less ene... | https://physics.stackexchange.com |
126,805 | [
"https://math.stackexchange.com/questions/126805",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/25553/"
] | ABCDEF is a regular hexagon and angle AOF= 90 degree.
FO is parallel to ED.
<img src="https://i.stack.imgur.com/bn6tq.jpg" alt="enter image description here">
What is the ratio of the triangle to the hexagon?
Give a hint so that i can get to the solution?
Thanks in advance.
| With regards to the first answer, as exceptionally well put as it was, I'd like to add a "caption answer" to it.<hr>
I assume you have some idea about a regular hexagon as being comprised of 6 congruent equilateral triangles. This implies that the Area of equilateral triangle $$A_\Delta=\frac16A_{\text{hex}}$$
Where $A... | $\hskip 1.7in$ <img src="https://i.stack.imgur.com/r0ePn.png" alt="hexagon">
| https://math.stackexchange.com |
46,935 | [
"https://dba.stackexchange.com/questions/46935",
"https://dba.stackexchange.com",
"https://dba.stackexchange.com/users/26323/"
] | Is there a DB that will allow a user to create a table with two fields, one calls <code>MYFIELD</code>, the other called <code>myfield</code>?
| Can you not just hook Crystal Reports to an instance of MS SQL Server? That way the process should be as simple as "backup the live database, restore it into test/snapshot location when needed".
If the database is less than 10Gb in size you can use SQL Express so there would be no licensing implications, if it is 10Gb... | This sort of thing is possible, but <em>painful</em>, with ETL tools like Talend Studio, Pentaho Kettle, or CloverETL.
Alternately, you could dump each table to CSV then <code>COPY</code> it into PostgreSQL, after manually converting the DDL.
Either way, DDL changes will be painful to keep in sync. You'll be way bett... | https://dba.stackexchange.com |
458,829 | [
"https://physics.stackexchange.com/questions/458829",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/166845/"
] | Let's take an example of magnetic field lines due to a current flowing through a wire. For the sake of the example, assume the wire of infinite length. Now, the magnetic field at any point radial to the wire can be derived. My question is, why are they lines and not a disc area? Why are the iron filings arranged in con... | First, I believe our question is really about how the iron filings are arranged, not about why magnetic field lines are lines. Field lines are abstract concepts which are by definition lines rather than disks (2d objects, or 3d if you allow thickness).
Why does a bunch of iron fillings form a pattern that traces the ... | <blockquote>
My question is, why are they lines and not a disc area? Why are the iron fillings arranged in concentric lines and not a disc with varying thickness, from more thick to less as the distance increases radially?
</blockquote>
The arrangement of the iron filings depends on how many filings you place and wh... | https://physics.stackexchange.com |
104,213 | [
"https://mathoverflow.net/questions/104213",
"https://mathoverflow.net",
"https://mathoverflow.net/users/25309/"
] | On a smooth algebraic variety X, every coherent sheaf F has a finite resolution by
locally free sheaves. Using such resolution, we can define the determinant
of F, det F, which is a line bundle on X.
My question is :
why if the support of F is of codimension greater or equal to 2
is the determinant of F trivial ?
It... | Outside the support of $F$, the resolution is an exact sequence, so the alternating tensor product of the determinants is trivial. On a smooth scheme, a line bundle trivial outside a codimension $2$ subset is trivial.
| Just an idea, using the first Chern class which should live in the cohomology with support in Supp($F$), you should then get that $c_1(F) = 0$ which makes $F$ trivial since it's a line bundle (perhaps modulo linear equivalence).
| https://mathoverflow.net |
32,586 | [
"https://stats.stackexchange.com/questions/32586",
"https://stats.stackexchange.com",
"https://stats.stackexchange.com/users/10468/"
] | Suppose you have a set of resistors R, all of which are distributed with mean μ and variance σ.
Consider a section of a circuit with the following layout: (r) || (r+r) || (r+r+r). The equivalent resistance of each part is r, 2r, and 3r. The variance of each section would then be $σ^2$, $2σ^2$, $3σ^2$.
What is the var... | The equivalent resistance $R$ of the entire circuit solves
$$
\frac1R=\sum_{i=1}^{3}\frac{1}{R_i}.
$$
One assumes that $R_i=i\mu+\sigma\sqrt{i}Z_i$, for some independent random variables $Z_i$, centered and with variance $1$.
Without further indications, one cannot compute the variance of $R$, hence, to go further, we... | This depends on the shape of the distribution for the resistance. Without knowing the distribution, I can't even say the average resistance, although I think there are constraints.
So, let's pick a distribution which is tractible: Let $s$ be the standard deviation of the resistance of one resistor. Let the resistance ... | https://stats.stackexchange.com |
146,112 | [
"https://stats.stackexchange.com/questions/146112",
"https://stats.stackexchange.com",
"https://stats.stackexchange.com/users/45188/"
] | If $X$ follows a normal distribution with parameters $\mu$ and $\sigma^2$ show that $Z = (X- \mu)/\sigma$ follows a standard normal distribution. This doesn't seem to intuitive to me. We shift $X$ so that the top of the bell curve is over $0$, that bit makes sense. But then we scale the curve by a scalar, wouldn't this... | Write $\displaystyle P\{Z \leq a\} = P\left\{\frac{X-\mu}{\sigma} \leq a\right\}
= P\{X\leq \mu+a\sigma\}=\int_{-\infty}^{\mu+a\sigma}f_X(x)\,\mathrm dx$ and then
make a <em>change of variable</em> in the integral, setting $z=\frac{x-\mu}{\sigma}$,
hopefully not forgetting to change the upper limit appropriately. <stro... | as I see you are thinking the area is divided by $$\sigma(standard deviation)$$ .....because Random Variable is divided by $\sigma$,
but $\sigma$ is also multiplied by all Probability function so the area remains same.
Now, for you second query disappearance of $\sigma$
as you Put $$X=Z\sigma+\mu$$ you must put $$dx=\... | https://stats.stackexchange.com |
144,649 | [
"https://mathoverflow.net/questions/144649",
"https://mathoverflow.net",
"https://mathoverflow.net/users/40042/"
] | If $X$ is a surface, projective and non-singular. Let $\mathbb{C}(X)$ be the function field of $X$. By a theorem of Siegel, we know that $trdeg_{\mathbb{C}}\mathbb{C}(X)\leq 2$. But how to argue that $trdeg_{\mathbb{C}}\mathbb{C}(X)= 2$？
| <strong>No, it is not always possible to make a strictly functorial choice of pullbacks.</strong> Four years later, I found a simple (if contrived) counterexample for this:
Let $\newcommand{\C}{\textbf{C}}\C$ be any full subcategory of $\textbf{FinSet}$ containing infinitely many sets of size 2, and at least one set o... | Many years ago, Peter Freyd published (I think he published it) a paper in which he showed that while it was possible to replace any category with products by a category with canonical products, the same could not be done for pullbacks. The only thing I remember about the paper was the use of the word "table" for some... | https://mathoverflow.net |
14,001 | [
"https://mathoverflow.net/questions/14001",
"https://mathoverflow.net",
"https://mathoverflow.net/users/1626/"
] | Let $z_1,\ldots,z_n$ be complex numbers of modulus one. Does it exist an increasing sequence $k_j\in\mathbb{N}$ such that $\lim_{j\to\infty}z_i^{k_j}=1$ for all i?
| Yes. Let $z=(z_1,...,z_n)$, a point on the torus $(S^1)^n$. Since the torus is compact, the sequence $z^m$ has a convergent subsequence $z^{m_1}$, $z^{m_2}$,..., and we may choose it so that $k_j=m_{j+1}-m_j$ are nonnegative and increasing. Then ${\rm lim} z_i^{k_j}=1$ for all $i$.
| Yes.
A standard lemma is that some element of $\{\alpha, 2\alpha, ..., m\alpha\}$ is within $1/(m+1)$ of 0 mod 1, since otherwise, there would have to be two multiples of $\alpha$ between some $k/(m+1)$ and $(k+1)/(m+1)$ which means their difference would be close to 1.
The same pigeonhole argument works on $(S^1)^n... | https://mathoverflow.net |
366,537 | [
"https://softwareengineering.stackexchange.com/questions/366537",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/297094/"
] | What should a constructor contain?
In both cases, all three arguments are needed for the class to work.
Which approach is better and why?
1)
<pre><code>class Language {
LanguageRepository languageRepository;
Language(LanguageRepository languageRepository) {
this.languageRepository = languageRepository;
}... | The best option seems <strong>1</strong> or <strong>3</strong>, but we need more details about what is the firstArg and secondArg. There are a lot of questions:
<ol>
<li>What is the purpose of the <code>Language</code> class? Is a Object? Is a helper class? Is some kind of Service class and the repository can be injec... | From what you asked, your class only seems to be a vehicle for calling <code>doThat()</code>. And <code>doThat()</code> needs three "parameters", a <code>languageRepository</code>, a <code>firstArg</code>, and a <code>secondArg</code>.
To me, "object-oriented" means that every single instance you have in your applicat... | https://softwareengineering.stackexchange.com |
2,745,595 | [
"https://math.stackexchange.com/questions/2745595",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/549182/"
] | To prove or give counterexample that $R \subset Dom(R) \times Ran(R)$
Let (a,b) \in R. So $a \in A$ and $b \in B$ where $R :A \rightarrow B$. Since Dom(R) is asubset of A. Let assume that $a \not \in Dom(R) $. So (a,b) doesnot belong to $ Dom(R) \times Ran(R)$
Is this correct ? Thanks for help
| If $(a,b)\in R$ then $a\in Dom(R)$ by the definition of "domain" and $b \in Ran(R)$ by the definition of "range", so $(a,b)\in Dom(R) \times Ran(R)$, so $R \subseteq Dom(R) \times Ran(R)$. QED
| I can see that you're trying to use a proof by contradiction, but it isn't very clear what you're trying to contradict. It's easier to use a direct proof, and it would look something like this:
<br/>
<strong>Proof.</strong> Let $R:A\rightarrow B$ be a mapping from $A$ to $B$ where $R=\{a\in A, b\in B: R(a)=b\}$. <br/>... | https://math.stackexchange.com |
2,794,328 | [
"https://math.stackexchange.com/questions/2794328",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/151735/"
] | For a topological space $(X, \mathcal{O})$, I want to show that for arbitrary $A \subset X$, int $A$ is open without using the fact that every open set contained in $A$ is contained in int$A$ and that $A$ is open iff $A =$int $A$.
int$A = \{x \in A | \exists U \in \mathcal{O} \text{ s.t. } x \in U, U \subset A\}$.
If... | If $a\in U_y$, then, since:
<ol>
<li>$U_y$ is an open set;</li>
<li>$a\in U_y$;</li>
<li>$U_y\subset A$,</li>
</ol>
$a\in\operatorname{int}A$.
| Instead of ruling out its being a boundary point, show directly that $a \in \operatorname{int} A$ by showing $\exists U \in \mathcal O$ such that $a \in U$ and $U \subset A$. Which $U$ can you use?
| https://math.stackexchange.com |
48,200 | [
"https://stats.stackexchange.com/questions/48200",
"https://stats.stackexchange.com",
"https://stats.stackexchange.com/users/19888/"
] | I have some questions about the Lasso.
<ul>
<li>After using the AIC or BIC to select a model, the model is fit with the variables selected in order to get the standard errors of the estimates with CIs, p-values etc...</li>
<li>When I use the Lasso approach, I try to do the same thing but the estimated values of the ... | Question 1 - There are two differences between the two approaches.
First, by estimating it all together you are constraining the variance of the random part to be the same for each of variables 1, 2 and 5. If you fit the three models separately you will have a different estimate of the variance each time. A useful t... | I suggest that you use a model with a limited dependent variable. For example ordered probit, multinomial logit, negative binomial ...etc. The model choice depends on what you are modelling.
| https://stats.stackexchange.com |
3,107 | [
"https://physics.stackexchange.com/questions/3107",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/1383/"
] | Is it correct to visualize operators existing as matrices parameterized by spacetime coordinates in the context of QFT?
| If you mean that QFT operators are matrices $M_{ij}$ whose indices $i,j$ are really points in space (or spacetime), so that the operator is really represented by the function $M(x,x')$, then the answer is No. The actual matrices corresponding to QFT operators are much much larger than that.
An object expressed by ... | Given that a quantum field is a field of operators and given that you can think of operators as (possibly infinite) matrices acting on a Hilbert (or, better, Fock) space, your assumption is correct. However, I wouldn't call it "visualizing" as I find operators more tangible than Matrices.
| https://physics.stackexchange.com |
638,793 | [
"https://electronics.stackexchange.com/questions/638793",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/324107/"
] | Can I connect 80 LEDs of 3 V each in series to a source of 220 V without using a resistor? Will it have impact on the LEDs if I run them for 24 hours?
| It was suggested I put my comment as an answer. So here it is:
No. Copper pour is a copper pour. As the words suggest it is an area filled with copper.
You may connect this copper to any net you like. Often GND, sometimes 0V, sometimes a voltage rail, sometimes to chassis. Depends on what you need.
Note that GND, 0V, C... | No, you can pour as much copper as you want and connect it anywhere you want or leave it unconnected.
So ground is only one of the options, but you must connect the pour where it makes most sense in an application.
| https://electronics.stackexchange.com |
585 | [
"https://mechanics.stackexchange.com/questions/585",
"https://mechanics.stackexchange.com",
"https://mechanics.stackexchange.com/users/365/"
] | I recently had the misfortune of having my 1997 4Runner's rear diff lock up because of a leak and then no gear oil.
Unfortunately to add to that the frame and major members are very rusted/rotted. (I had a new rear end to put in, but would take A LOT of labor) to replace because nothing unbolts and bolts nicely.
S... | I have my 1990 Toyota V6 3.0 extra cab running on the front two wheels only, I had the same thing happen. I was told, a friend of mine, drove a similar truck all the way from the desert into San Diego.
I've been driving the truck all morning, the deal is, I have a "High" 4x4 and a "Low" 4x4, right now I have it engage... | I would really question this approach for these reasons:
<ul>
<li>The vehicle wasn't designed to run in 4WD full time. This may put extra strain on the frontend and wear out your front drivetrain and other components.</li>
<li>The vehicle wasn't designed for the front-wheel drive to handle all of the force of moving ... | https://mechanics.stackexchange.com |
1,056,610 | [
"https://math.stackexchange.com/questions/1056610",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/174717/"
] | Give a combinatorial argument to prove that the number of derangements
satisfies the recursive formula $d_n = (n − 1)(d_{n−1} + d_{n−2})$ for $n ≥ 2$. (Hint:
For a derangement $σ$, consider the integer $k$ with $σ(k) = 1$. Argue based on
the number of choices for $k$ and then whether $σ(1) = k$ or not.)
I tried workin... | SKETCH: Let $\sigma$ be a derangement of $[n]=\{1,\ldots,n\}$, and suppose that $\sigma(k)=1$. There are two possibilities.
<ul>
<li>$\sigma(1)\ne k$: Define a function $$\tau:[n]\setminus\{1\}\to[n]\setminus\{1\}:\ell\mapsto\begin{cases}\sigma(\ell),&\text{if }\ell\ne k\\\sigma(1),&\text{if }\ell=k\;.\end{cas... | We seperate into two cases.
Case 1: Let $i$ be the image of $1$, case one is when $1$ is the image of $i$, There are $n-1$ possible values for $i$. And once $i$ has been selected there are $d_{n-2}$ ways to biject the remaining numbers.
Case 2: The image of $i$ is not $1$. Then every element has exactly one forbidden... | https://math.stackexchange.com |
722,437 | [
"https://physics.stackexchange.com/questions/722437",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/123183/"
] | I was taught that Internal Energy <span class="math-container">$U$</span> is a relative quantity: only changes in <span class="math-container">$U$</span> are meaningful. It doesn't have an absolute value, since it always comes with an arbitrary constant (for example <span class="math-container">$U = nT +c$</span>).
En... | It's true that the temperature <span class="math-container">$T$</span>, entropy <span class="math-container">$S$</span>, pressure <span class="math-container">$P$</span>, volume <span class="math-container">$V$</span> and amount of material <span class="math-container">$N$</span> are all amenable to being modeled as ab... | Energy and entropy are not directly measurable. Only <em>differences</em> may be measured. It is enough to think about typical energy measurements via work and heat measurements (always referring to an initial and a final state).
The third principle of thermodynamics only states that the limit of the entropy for temper... | https://physics.stackexchange.com |
357,290 | [
"https://mathoverflow.net/questions/357290",
"https://mathoverflow.net",
"https://mathoverflow.net/users/156112/"
] | I've been trying to prove (maybe even disprove) the following inequality:
<span class="math-container">$$
\sum_{n=1}^{N} \frac{a_n}{\sqrt{\sum_{i=1}^{n}a_i}} \leq C \sqrt{\sum_{n=1}^{N}a_n}
$$</span>
Where <span class="math-container">$ a_1,...,a_N\geq 0 $</span> are some non-negative numbers, and <span class="math-co... | For every <span class="math-container">$n\in\{1,\dotsc,N\}$</span>, we have
<span class="math-container">$$2\sqrt{\sum_{i\leq n} a_i}-2\sqrt{\sum_{i\leq n-1} a_i}=\frac{2a_n}{\sqrt{\sum_{i\leq n} a_i}+\sqrt{\sum_{i\leq n-1} a_i}}>\frac{a_n}{\sqrt{\sum_{i\leq n} a_i}}.$$</span>
Summing these up, we obtain the inequal... | Rewrite your inequality as
<span class="math-container">$$lhs:=\sum_{n=1}^N \frac{s_n-s_{n-1}}{\sqrt{s_n}}\le C\sqrt{s_N},$$</span>
where <span class="math-container">$s_n:=\sum_{i=1}^n a_i$</span>. Note that
<span class="math-container">$$\sum_{n=1}^N \frac{s_n-s_{n-1}}{\sqrt{s_n}}$$</span>
is a lower Riemann sum fo... | https://mathoverflow.net |
109,587 | [
"https://electronics.stackexchange.com/questions/109587",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/10023/"
] | Please someone explain to me in Simple English or Basic equations as to why does a <code>Transverse Electric and Magnetic Modes(TEM)</code> propagate on only two surface Wave guide like a <code>coaxial or a parallel plate</code> wave guide?
| The paper you linked to (despite spelling and language errors) is actually pretty good. From page 4 ... " ... all transverse components of E and H can be determined from only the axial components Ez and Hz." For TEM mode support you need to have BOTH Ez=Hz=0 simultaneously. The paper deals with the mathematic reason... | That's because, the only way to propagate a TEM mode along a specific path is by flowing a physical current also along that specific path. To produce a current, you also need a physical voltage. Therefore you need 2 conductors.
Moreover, this is not the case with TE and TM modes, as they are able to manifest and be gu... | https://electronics.stackexchange.com |
393,317 | [
"https://stats.stackexchange.com/questions/393317",
"https://stats.stackexchange.com",
"https://stats.stackexchange.com/users/140365/"
] | I have data from one group (<span class="math-container">$n = 25$</span>) of subjects pre- and post- tested on an <span class="math-container">$15$</span>-item dichotomously scored test (see below).
Given that the data are from the same subjects (i.e., correlated), how can I correctly use <strong><em>count regression<... | This isn't what's typically meant by "count data" in statistics. When statisticians talk about count data, they are referring to non-negative whole numbers that have no upper limit (<span class="math-container">$[0, \infty)$</span>). Your data are bounded counts (counts out of a finite total). They are bin... | You should use the Wilcoxon signed-rank test, which is essentially a non-parametric version of the paired t-test. In R, you would run
<pre><code>wilcox.test(pre, post, paired=TRUE)
</code></pre>
You could also run a paired t-test (ignoring the count nature of the data) using <code>t.test()</code>, which will yield th... | https://stats.stackexchange.com |
164,593 | [
"https://physics.stackexchange.com/questions/164593",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/56321/"
] | Why does hot air rise?
I did an experiment:
I made a model of hot air and cool air with marshmallows and toothpicks.<br>
The hot air had more volume than the cold air.<br>
Then, I weighed it.<br>
They both weighed the same, even though they had a different volume.
So I don't understand why does hot air rise?
| Consider each molecule.
As you say, masses $m$ are constant but volumes usually grow with higher temperature.
That hot air molecules will float up is not do to any changes in mass or so - but to changes in <em>density</em> $\rho$:
$$\rho=\frac{m}{V}$$
The fluid of <strong>highest density</strong> will seek the <str... | Due to Charles law, the volume of the gas is directly proportional to the temperature of the gas,
<span class="math-container">$$ V \propto T $$</span>
or
<span class="math-container">$$ \frac{V}{T} = k $$</span>
Therefore, when the temperature of the gas is increasing, the volume of the gas is increasing as well. ... | https://physics.stackexchange.com |
3,460,394 | [
"https://math.stackexchange.com/questions/3460394",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/707081/"
] | <span class="math-container">$$\sum_{n=1}^\infty \frac{4n}{(n+1)(n+2)(n+3)} = 1$$</span>
The hint my teacher game me was to use partial fractions and observe it is a telescoping sum, but I can´t see how the elements of the sum cancel out.
edit:
The partial fractions I got were:
<span class="math-container">$$\frac{-2... | <strong>HINT</strong>
We have that
<span class="math-container">$$\frac{4n}{(n+1)(n+2)(n+3)}=-\frac{2}{n+1}+\frac{2}{n+2}+\frac{6}{n+2}-\frac{6}{n+3}$$</span>
| The telescoping works as follows:
<span class="math-container">$$\begin{align}
n\to&-\frac2{n+1}+\frac8{n+2}\color{green}{-\frac6{n+3}}\\
n+1\to&-\frac2{n+2}\color{green}{+\frac8{n+3}}-\frac6{n+4}\\
n+2\to&\color{green}{-\frac2{n+3}}+\frac8{n+4}-\frac6{n+5}\\
\end{align}$$</span>
and the green terms cance... | https://math.stackexchange.com |
370,595 | [
"https://electronics.stackexchange.com/questions/370595",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/186922/"
] | I'm designing a modular board, where the two modules are connected through pin headers. For mechanical stability I have more pins than traces and my question is that which is the better: route each trace through one pin and leave the remaining pins free or route the traces through multiple pins?
In the case of power t... | From the abstract of your second link:
<blockquote>
Loop unrolling is the main compiler technique that allows reconfigurable architectures [to] achieve large degrees of parallelism. However, loop unrolling increases the area and can potentially have a negative impact on clock cycle time. In most embedded application... | 'Loop Unrolling' is a systematic method of achieving parallelism that can be automated.
In the bad old days, we wrote machine code, then assembler, then simple compiled languages, then rich languages with useful libraries. This allowed us to write at a progressivley higher level, and let an automatic process take car... | https://electronics.stackexchange.com |
380,264 | [
"https://softwareengineering.stackexchange.com/questions/380264",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/318071/"
] | This is a concept related question.
I'm writing a program polling for alerts on various devices, there are two different type of alerts i need to poll, reds and oranges.
My approach is to create two threads, each polling their type of alerts independently.
I thought about using threads because both polling functions ... | If these API calls are blocking calls to a third-party library you can't control, this threading model is roughly the best you can do.
If the API library is yours and is just doing socket read/select or whatever, you don't really need multiple threads, and can use a single-threaded Reactor. Even if you really need to ... | There is no simple answer to your question. It depends on the details of your classes. Before giving the answer, you have to clarify some points:
<ul>
<li>Do the threads share data with other threads?
If so, you have to take care that the data is only accessed by one thread at a time. This normally is done by synchron... | https://softwareengineering.stackexchange.com |
28,689 | [
"https://electronics.stackexchange.com/questions/28689",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/8855/"
] | In one of my classes we are learning about circuits. For homework, we have to create a finite state machine for a vending machine using an SR flip-flop. The machine can either take a nickel, dime, or nothing until it gets to at least 15 cents, so it has 4 states (0, 5, 10, and 15 cents). Once the machine receives 15 ce... | The reset, given the truth table you provided, happens just because the state <strong>11</strong> of the state machine is mapped in the state <strong>00</strong>; in fact, if you look at the outputs, both states have the same next state, so if the inputs are <strong>00</strong> (buffer), from the state <strong>11</stro... | Depending upon how the coin sensors and output of the machine are implemented, you might need some more states to allow for the fact that a coin might be hitting a switch for an arbitrary length of time; I don't see anything in your machine to handle that. It's also not clear how long the "dispense product" output is ... | https://electronics.stackexchange.com |
22,644 | [
"https://dba.stackexchange.com/questions/22644",
"https://dba.stackexchange.com",
"https://dba.stackexchange.com/users/3898/"
] | I've been working on code in T-SQL to add new schedules to a SQL Agent job using the sp_add_jobschedule proc in the msdb database. When I add a new schedule (typically a run-once at a specific date/time) and immediately look at the values in sysjobschedules and sysschedules, I can see that the new schedule has been a... | <h2><strong>Short Answer</strong></h2>
It looks like the data in <code>msdb.dbo.sysjobschedules</code> is updated by a background thread in SQL Agent, identified as <code>SQLAgent - Schedule Saver</code>, every 20 minutes (or less frequently, if <code>xp_sqlagent_notify</code> has not been called and no jobs have run i... | <code>msdb.dbo.sp_help_job</code> always appears to return the correct actual <code>next_run_date</code> / <code>next_run_time</code>.
It uses <code>sp_get_composite_job_info</code>, which does the following call to actually retrieve the <code>next_run_date/time</code>.
<pre><code> IF ((@@microsoftversion / 0x01... | https://dba.stackexchange.com |
28,480 | [
"https://stats.stackexchange.com/questions/28480",
"https://stats.stackexchange.com",
"https://stats.stackexchange.com/users/8137/"
] | It seems the Bonferroni method (dividing experimentwise alpha by # of comparisons) for choosing the p level to fix the experimentwise alpha (when doing many pairwise comparisons) is more conservative than just solving $1 - (1 - p)^k = .05$ to get the alpha to use for each of the $k$ pairwise comparisons. Why not just ... | The Dunn-Sidak approach (your second equation) is only valid if your contrasts are <em>orthogonal</em>, whereas the Bonferroni adjustment is guaranteed to always hold your experimentwise alpha below your chosen value. In addition, with only a few contrasts, both methods will yield almost identical values. When combin... | Gung gave an excellent answer. i just want to add that nothing is simpler than dividing alpha by n (the number of tests). Although Bonferroni is conservative it is easy to use and does not require added assumptions as Sidak and others do. Now it is bad when individual p-values are realtively large or n gets very lar... | https://stats.stackexchange.com |
614,156 | [
"https://physics.stackexchange.com/questions/614156",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/273618/"
] | Im studying statistical mechanics and came across the ensembles.
<ol>
<li>Now system of large number of particles can be defined by an ensemble which contains elements (infinite of them) where each element is the mental copy of system at a particular time and time average of any quantity of system can be assumed as sam... | We don't know for certain what is inside the event horizon of a black hole, but we expect there to be fields inside the event horizon that are just extensions of the fields outside of the event horizon. The only restriction is that events that happen inside the event horizon cannot be causally linked to effects outside... | Sure, the reisner-Nordström solution is given by:
<span class="math-container">$$ds^{2} = -f(r)dt^{2} + \frac{1}{f(r)}dr^{2} + r^{2}d\theta^{2} + r^{2}\sin^{2}\phi^{2}$$</span>
where
<span class="math-container">$$f = 1 -\frac{2M}{r} + \frac{q^{2}}{r^{2}}$$</span>
This is a solution to the Einstein-Maxwell equations wi... | https://physics.stackexchange.com |
144,069 | [
"https://physics.stackexchange.com/questions/144069",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/63256/"
] | Considering a focused laser beam of 1000mW power, it will burn paper or wood slightly.
Focussing the light of an 1000mW LED does not do so. Why is that?
Is it because the laser is monochromatic? What makes the difference?
| You need a better lens. Seriously, which is to say that the LED is dumping its output power into a large solid angle, so re-collecting it all is rather difficult.
Also, are you certain you're quoting the mean output power of both devices? If that's their peak power, the LED's mean power could be far less if (as wi... | What matters is the power per unit area. The reason the laser can burn is that the laser, being well collimated, can be focused to a much smaller point than the LED. As the power from the LED is spread over a larger area in the source emitter, the optical invariant prevents one from focusing this to a small point while... | https://physics.stackexchange.com |
414,208 | [
"https://electronics.stackexchange.com/questions/414208",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/208441/"
] | I have a laptop charger which has 19.5 V 3.33 A output. I want to use it for raspberry, which needs 5V and 2.5A and for monitor which needs 12V 3A. Is that charger strong enough to run the whole system? Is it possible to convert 19.5V 3.33A with a buck step down to 12V 5.5A which will be connected to monitor and then u... | Yes, it is possible
power of laptop charger is = 19.5 * 3.33 = 65 Watts
<strong>your loads power:</strong>
<ol>
<li>raspberry pi = 5*2.5 = 12.5 watts
</li>
<li>Display = 12 * 3 = 36 watts
total power = 48.5 watts
</li>
</ol>
Total power < power of charger,
you can use it. it will work
| The answer to your header question is NO!
Input 19.5x3.33 = 64.935 Watts.<br>
Output 12x5.5 = 66 Watts.
So your new output power is higher then your input power which is against the law of conservation of energy.
<hr>
But according to your question details your equipment requires only 48.5 Watts.
That is do-able b... | https://electronics.stackexchange.com |
43,353 | [
"https://dsp.stackexchange.com/questions/43353",
"https://dsp.stackexchange.com",
"https://dsp.stackexchange.com/users/27261/"
] | Say I have two 1000-point sequences. I can compute the entire convolution fairly efficiently using FFTs (keeping in mind that zeroes have to be padded on to avoid doing a circular convolution).
However, I'm only interested in about 500 points in this convolution. To be more specific, say the indices of the convolution... | I'll write names of time domain sequences in lower case and their frequency-domain counterparts in upper case, for example $X = \operatorname{DTFT}(x)$, where $\operatorname{DTFT}$ stands for discrete-time Fourier transform. I chose this transform, because it is unaffected by zero-padding of the time-domain sequences, ... | Given two discrete time sequences $x[n]$ and $h[n]$ which have lengths of $1000$ points each, their <strong>linear</strong> convolution $z[n] = x[n] \star h[n]$ will have a length of $L_z = 1000 + 1000 -1 = 1999$ pts.
The theory of DTFT (discrete-time Fourier transform) provides a relationship between the <strong>line... | https://dsp.stackexchange.com |
114,390 | [
"https://mathoverflow.net/questions/114390",
"https://mathoverflow.net",
"https://mathoverflow.net/users/29381/"
] | Im trying to prove a generalization of the Radon Nykodym theorem, but im having troubles even for finite measures, could someone help?
Let $\mu$ and $\nu$ two $\sigma$-finite measures in $\(X,\mathcal{F})$. If $\nu$ << $\mu$, then there exists a non-negative function $h \in L^1(X,\mu)$, such that for every funct... | If you assume you have proven the Radon-Nikodym theorem for measures $\mu,\nu$, $\nu <<\mu$, then for any $F$ in such a class, the measure $\mu_F,\nu_F$ defined by
$\mu_F(E):=\int_E F(x)\;d\mu$,
$\nu_F(E):=\int_E F(x)\;d\nu$,
then since $\nu_F << \mu_F$ (if your definition of absolute continuity is equ... | If $h$ is a density of $\nu$ w.r.t. $\mu$ then $\int F d\nu = \int Fh d\mu$ holds
for all indicator functions (just by the definitions of a density and the integral).
This extends to simple measurable functions (taking only finitely many positive values)
by linearity and then to all positive measurable functions by mon... | https://mathoverflow.net |
65,199 | [
"https://physics.stackexchange.com/questions/65199",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/22908/"
] | It is more likely for an area with higher atmospheric pressure to be sunny. In the same way, it is more probable in low-pressure areas for it to rain.
This is because of the law which states <span class="math-container">$pV=(c)T$</span> where <span class="math-container">$p$</span> is pressure, <span class="math-conta... | Generally speaking low and high pressure areas are associated with vertical movement of the air. Air rises in a low pressure area and falls in a high pressure area. In a low pressure area the rising air cools and this is likely to condense water vapour and form clouds, and consequently rain. The opposite is true in a h... | An increase in pressure is not what causes condensation and rain.
Besides, the formula $pV = \text{const}$ applies to an isolated sample of a fixed amount of gas at a fixed temperature. Those conditions don't hold true for air in the atmosphere.
The real reason it rains is quite complicated, but the gist of it is tha... | https://physics.stackexchange.com |
60,895 | [
"https://datascience.stackexchange.com/questions/60895",
"https://datascience.stackexchange.com",
"https://datascience.stackexchange.com/users/67537/"
] | Hi I am developing a reinforcement learning agent for a continous state/discrete action space. I am trying to use boltmzann/softmax exploration as action selection strategy. My action space is of size 5000.
My implementation of boltzmann exploration:
<pre><code>def get_action(state,episode,temperature = 1):
state... | This is an ideal case for feature engineering!
I did this same case for myself using the google takeaway data to predict whether I am at home or at work.
Instead of just using time I extracted the following features:
<ol>
<li>Work Day --> 1 / 0</li>
<li>Day of the Week</li>
<li>Month</li>
<li>Year</li>
<li>Time</li>... | Choose any classifier you like and which fits your requirements...would be the "easy" answer :D
Your problem sounds as if you could go for an easy algorithm for classification up to complicated ones depending on which additional features you want to use. From the top of my head seasonal features could be interesting: ... | https://datascience.stackexchange.com |
4,631,879 | [
"https://math.stackexchange.com/questions/4631879",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/1146348/"
] | The correct answer to the integral above should be <span class="math-container">$\int \frac{f'}{f} dx= \ln(f)$</span>. Yet if one applies integration by parts according to
<span class="math-container">$\int u \frac{dv}{dx} = u v - \int v \frac{du}{dx} dx$</span>
then setting <span class="math-container">$u = \frac{1}{f... | The correct answer is
<span class="math-container">$$\int \frac{f'(x)}{f(x)}dx= \log |f(x)|+C$$</span>
not <span class="math-container">$\log |f(x)|$</span>.
| Let's assume, for simplicity, that <span class="math-container">$f$</span> is continuous over the interval <span class="math-container">$(a,b)$</span> (and nonzero).
If <span class="math-container">$c\in(a,b)$</span>, an antiderivative of
<span class="math-container">$$
g(x)=\dfrac{f'(x)}{f(x)}
$$</span>
is
<span class... | https://math.stackexchange.com |
225,335 | [
"https://stats.stackexchange.com/questions/225335",
"https://stats.stackexchange.com",
"https://stats.stackexchange.com/users/43084/"
] | Reading up on the Neyman Pearson Lemma, I have a question about how to obtain the probability for a type I error, $\alpha$, when we establish a threshold $\eta$ for the liklihood ratio $\Lambda(x)=\frac{ L(x \mid \theta _0)}{ L (x\mid\theta _1)} \leq \eta$.
The probability of a type I error (rejecting the null-hypothe... | By popular request, I am reposting my comments as an answer.
The way you wrote it originally, $0.3$ probability of being paid in October is (already) conditional on not being paid in September. It (0.3) can not be the unconditional probability of being paid in October, because this would imply the unconditional proba... | The question was answered in the comment section by Mark L. Stone and broncoAbierto.
From broncoAbierto:
<blockquote>
The first part is correct. You can interpret it intuitively the following way. The chances of getting paid in September have a 7 to 1 ratio with respect to the chances of getting paid any other time... | https://stats.stackexchange.com |
152,091 | [
"https://dba.stackexchange.com/questions/152091",
"https://dba.stackexchange.com",
"https://dba.stackexchange.com/users/34065/"
] | We are having memory pressure issues (<code>RESOURCE_SEMAPHORE</code> waits) on one of our servers but there are very few active connections going on at one time. Logically, it wouldn't seem like sleeping connections would hold on to memory but I'm wondering if they actually do? IderaDM shows several sleeping connecti... | If you're trying to track down memory usage and what queries are the biggest offenders, run through the following steps:
<ol>
<li>Identify what DB on the instance is consuming the most memory
<pre><code>-- DB using most cache
DECLARE @total_buffer INT
SELECT @total_buffer = cntr_value
FROM sys.dm_os_performance_co... | I use the below query with nothing excluded because I want to see where the SQL Server background waits are and they will all be at the same percentage. Items like <code>HADR_FILESTREAM_IOMGR_IOCOMPLETION</code>, <code>XE_TIMER_EVENT</code>, and <code>REQUEST_FOR_DEADLOCK_SEARCH</code>. If your <code>RESOURCE_SEMAPHO... | https://dba.stackexchange.com |
71,155 | [
"https://electronics.stackexchange.com/questions/71155",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/1814/"
] | Can somebody explain how this circuit works?
<img src="https://i.stack.imgur.com/8BjSa.png" alt="schematic">
<ol>
<li>The OP tries to make the same voltage at the input cables.</li>
<li>At first, the LED is on. Therefore we have a low voltage (maybe 1V) on the negative input</li>
<li>The positive input also get this ... | Yes - I totally agree with Olin its a messed up circuit - just goes to show you shouldn't believe everything you read. I think the actual circuit should have been - <img src="https://i.stack.imgur.com/eYPKa.jpg" alt="enter image description here">
| No, since this circuit is a mess and underterministic.
Note the positive input driven only thru a capacitor to ground. Unless this is some special opamp that biases the postive input in some known range (there are actually amps that do that, usually meant for audio applications), the voltage on the positive input is ... | https://electronics.stackexchange.com |
48,951 | [
"https://mathoverflow.net/questions/48951",
"https://mathoverflow.net",
"https://mathoverflow.net/users/1540/"
] | It is asserted in <em>A Course in Metric Geometry</em> by Burago, Burago, Ivanov that
<blockquote>
there can be no more than continuum of mutually nonisometric compact spaces
</blockquote>
How is this proven?
Its clear that there must be at least a continuum of mutually nonisometric compact spaces, i.e. $([0,\alp... | I think "compact" can be even weakened here to "separable and complete" (and regarding your first guess, total boundedness is essentially used to prove that compact implies separable). Here's a sketch: any such space is determined, up to isometry, by the restriction of the metric to a countable dense subset. Thus the... | Since a compact metric space is in particular separable, its type of isometry is determined by a dense countable subspace. There are continuum many distances on , say $\mathbb{N}$.
| https://mathoverflow.net |
224,113 | [
"https://mathoverflow.net/questions/224113",
"https://mathoverflow.net",
"https://mathoverflow.net/users/18974/"
] | Consider a sequence $V_N$ of subspaces of $\ell^N_1$ so that $\dim V_N = N- n$ and $n$ is $\mathsf{o}(N)$. Is it true that these spaces are "thick" (unofficial terminology), i.e. are there constants $K_1,K_2>0$ so that for $N$ large enough,
$$
\sup_{x \in V, \|x\|_1 \leq K_1} \|x\|_\infty \geq K_2
$$
where $\|x\|_\i... | Improved version of my answer. The following version of Kashin's
(1977) result is needed here: For any $\alpha\in(0,1)$ there
exists $C=C(\alpha)$ such that for any $N$ there is an
$\lceil\alpha N\rceil$-dimensional subspace $L$ of $\ell^N_1$
satisfying
$$\forall x\in L\quad
\frac1{\sqrt{N}}||x||_1\le||x||_2\le\frac{C... | I discussed this question with Pisier over lunch. He later called my attention to the paper
[GG] Garnaev, A. Yu.; Gluskin, E. D.;
The widths of a Euclidean ball. (Russian)
Dokl. Akad. Nauk 277 (1984), 1048–1052.
Pisier emailed me,
“They get an equivalent of the relevant Kolmogorov numbers
of inclusion of $n$-dim E... | https://mathoverflow.net |
175,027 | [
"https://electronics.stackexchange.com/questions/175027",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/78541/"
] | I have a circuit where a LED has its cathode connected to the collector of my C8050 (or SS8050) NPN transistor, with the emitter grounded.
Even though the base is left floating, the current is still flowing freely to the emitter.
Applying any current/voltage to the base doesn't change anything.
Here's the circuit:
<im... | 8050 transistors are made with the Japanese and the American style pinouts- it is not a JEDEC or JIS registered part.
Looks like the one you happen to have has the Japanese pinout.
E C B
| No, that's not how it should work; with the base floating the transistor should not conduct.
My first guess would be that you connected it wrong. It's important to note that different transistors have different pinouts, make sure you refer to the datasheet for the C8050, and not some other transistor.
If you would mi... | https://electronics.stackexchange.com |
198,513 | [
"https://softwareengineering.stackexchange.com/questions/198513",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/43961/"
] | Let's assume the modeling of <code>User</code> model in a context of a social network.
User concept is composed of two notions:
<ul>
<li>Authentication elements like userName/Password/Email etc...</li>
<li>Extra data information sometimes called "User profile" like firstName, birthday, pictures etc..</li>
</ul>
At f... | IMO this is a false dichotomy. If you follow SRP, you keep your system simple overall. Multiple small classes tend to be more "simple" (in many cases) rather than fewer large classes. Plus it seems like you are conflating two issues: how you design your classes vs. how you design your database. The two do not need to b... | You're confusing KISS; simple isn't referring to simple to <em>implement</em> for the developer, it refers to simple design, simple to understand and use. Following SRP makes your code simpler to understand and use because it's simpler to use a purpose built class for a single purpose than a multipurpose class, it's al... | https://softwareengineering.stackexchange.com |
1,084,326 | [
"https://math.stackexchange.com/questions/1084326",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/203362/"
] | <h2>$\sum_{k=1}^{n}k\binom{n}{k} = n2^{n-1}$</h2>
I have tried both induction and transforming both sides to get equality but no luck
I know that
$\sum_{k=1}^{n}\binom{n}{k} = 2^{n}-1$
and $\sum_{k=1}^{n}k=\frac{n(n+1)}{2}$
p.s: I couldn't find something similar of this kind anywhere. But I thinks it's something t... | <strong>Given:</strong> $\text{S} \ = \displaystyle\sum_{k=1}^{n}k\binom{n}{k}$
$=\displaystyle\sum_{k=1}^{n}k\times\dfrac{n}{k}\binom{n-1}{k-1}$
$=n\displaystyle\sum_{k=1}^{n}\binom{n-1}{k-1}$
$= \boxed{n \ 2^{n-1}}$
| You can use $\binom{n}{k} = \binom{n}{n-k}$:
$$
\begin{align*}
2\sum_{k=0}^n k\binom{n}{k} &= \sum_{k=0}^n k\binom{n}{k} + \sum_{k=0}^n k\binom{n}{n-k} \\ &= \sum_{k=0}^n k\binom{n}{k} + \sum_{k=0}^n (n-k)\binom{n}{k} \\ &= \sum_{k=0}^n [k+(n-k)]\binom{n}{k} \\ &= \sum_{k=0}^n n\binom{n}{k} \\ &= n2... | https://math.stackexchange.com |
563,274 | [
"https://physics.stackexchange.com/questions/563274",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/214316/"
] | So I'm trying to understand velocity time dilation, even still after brushing it multiple times throughout university. I am doing so with the example of a spaceship travelling to Alpha Centauri [AC].
Lets approximate both the Earth and AC to be stationary, the distance between Earth and AC to be be <strong>4ly</strong>... | Wolframalpha is likely the source of confusion here: the initial condition is the term with <span class="math-container">$n=1$</span>, i.e. <span class="math-container">$A_1 = 1$</span>, whereas all others are <span class="math-container">$A_n=0$</span>. The equation for the initial condition is one equation with the i... | Your solution <span class="math-container">$A_n$</span> isn't zero for <em>every</em> <span class="math-container">$n$</span>. Looking at your initial conditions you might expect there to be only one non-zero coefficient since the IC already have the form of a sine wave. When <span class="math-container">$n=1$</span> y... | https://physics.stackexchange.com |
325,447 | [
"https://physics.stackexchange.com/questions/325447",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/143579/"
] | As the charge on electron is $$e^-=-1.6\times10^{-19}C$$ and charge on proton is $$p^+=+1.6\times10^{-19}C$$
<blockquote>
Does this mean that the charge on electron is $3.2\times10^{-19}C$ less than that of charge on proton?
</blockquote>
| No, The magnitude of charge on both the particles is same but opposite sign.
Actually the negative sign doesn't always mean "less", especially in physics. So, the charge on $e^-$ is not smaller than that of $p^+$.
| The sign has nothing to do with the charge itself. It is just a convention. Just because we write an electron's charge as $-1.6\times10^{-19}$, it does not make the electron negative or its charge to be less than that of a proton.
We could have called charge on a proton to be $-1.6\times 10^{-19} C$ and the charge on ... | https://physics.stackexchange.com |
168,427 | [
"https://softwareengineering.stackexchange.com/questions/168427",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/51966/"
] | Can you think of some reasons that the management force the developers to write and call Stored Procedures instead of inline SQL statements directly?
Even a very simple CRUD statement, writing a stored procedure takes more time and create extra workload.
| One of the reasons might be due to the fact that old habits die hard.
In older databases, stored procedures used to usually perform better due to caching of the query plan for stored procedures in comparision to ad-hoc queries which did not usually get cached. A lot of newer (i mean databases in the last 5 - 6 years)... | Well, because you'd like to keep your job is always a pretty good reason. If that's the company's/team's/management's standard, it's your job to conform to it.
The Stored Procedure vs. Client Side query argument is quite old at this point and there enough pluses and minuses for each that it's a matter of preference as... | https://softwareengineering.stackexchange.com |
514,885 | [
"https://physics.stackexchange.com/questions/514885",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/196626/"
] | The way i interpret pseudo-forces is that its a mathematical correction that makes the conclusion of the observer in an accelerated frame correct.
And I also believe that this "pseudo-force" has no physical significance, that is, it isn't something actually acting on the body being observed.
While doing circular moti... | You are correct that pseudo-forces can be viewed as a mathematical correction to allow for Newton's second law to work in non-inertial reference frames, and I tend to think of it as such most of the time. However, really these pseudoforces are the effects of inertia. They aren't forces, but they still are a property of... | You actually <em>don't</em> feel any such outward force.
Remove the car from the scenario, and you will realise that you are in fact not pushed outwards, but just continuing straight ahead. The car is pulled in so it turns, but you aren't. In other words:
<ul>
<li>the car is moving <em>away from underneath you</em>,... | https://physics.stackexchange.com |
348,736 | [
"https://mathoverflow.net/questions/348736",
"https://mathoverflow.net",
"https://mathoverflow.net/users/147728/"
] | Let <span class="math-container">$A$</span> be a unital algebra, defined over the complex numbers. Any bimodule <span class="math-container">$M$</span> over <span class="math-container">$A$</span> must, by definition, be a left, and right, module satisfing
<span class="math-container">$$
a.(m.b) = (a.m).b, ~~~~~~~ \tex... | Suppose <span class="math-container">$A$</span> is a non-commutative Hopf algebra. Then you can use <span class="math-container">$M=A$</span> with the left adjoint and right regular actions:
<span class="math-container">$$
a\cdot m = \sum_{(a)}a_{(1)}mS(a_{(2)}), \ m\cdot b = mb .
$$</span>
In particular, you can use t... | <span class="math-container">$\newcommand{\C}{\mathbb C}$</span>
Let <span class="math-container">$G$</span> be a nonabelian group and <span class="math-container">$\rho\colon G\to\mathrm{Aut}(V)$</span> be a faithful representation of <span class="math-container">$G$</span> over <span class="math-container">$\C$</span... | https://mathoverflow.net |
82,908 | [
"https://physics.stackexchange.com/questions/82908",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/31810/"
] | <img src="https://i.stack.imgur.com/TbAeS.jpg" alt="enter image description here">
Why is (m)(v)=Impulse or as they put it here, Vs = I/Ms?
Shouldn't (m)(v) be equal to momentum, not I?
I don't understand why that is the solution. I was trying to solve for relative velocities, V2f - V1f, using momentum conservation... | Let $\mathbf F_s(t)$ and $\mathbf F_b(t)$ denote the forces exerted on the sattelite and booster during the explosion respectively. Let the explosion take place during the time interval $[t_1, t_2]$, then the impluses experienced by the satellite and booster during the explosion equal the changes in their momenta;
\be... | Firstly, remember that impulse= change in momentum= mv-mu
Suppose the satellite and the rocket before explosion was moving with velocity of u
Thus total momentum= 950*u+ 640*u
During explosion,impulse exerted on each other is the same (350Ns) but opposite in direction (Remember, Newton's third law states that the fo... | https://physics.stackexchange.com |
4,558 | [
"https://cstheory.stackexchange.com/questions/4558",
"https://cstheory.stackexchange.com",
"https://cstheory.stackexchange.com/users/-1/"
] | There is a theorem that states a function $f$ can be computed with a Turing-machine in time $O(g)$ with primitive recursive $g$ (of the length of input) iff $f$ is primitive recursive.
Where can I find a reference for this theorem? Wikipedia seems to state it but gives no references, nor does my books.
| This is known as a <em>Ritchie-Cobham</em> property, or a <em>honesty</em> property of primitive-recursive functions. See for instance Theorem VIII.8.8, page 297 in P.G. Odifreddi, <em>Classical Recursion Theory</em>, vol. 2, 1999.
Odifreddi refers to
<ul>
<li>Kleene, General recursive functions of natural numbers, ... | You can look at:
A. Grzegorczyk. <em>Some classes of recursive functions.</em> Rozprawy Matematyczne, (IV), 1953.
R. W. Ritchie. <em>Classes of predictably computable functions.</em> Trans. A.M.S., 106:139–173,
1963.
(I don't know if you can find them for free in Internet).
Or download the Robert Daley's Lecture No... | https://cstheory.stackexchange.com |
159,779 | [
"https://softwareengineering.stackexchange.com/questions/159779",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/61139/"
] | As a fresh programmer, one of the first thing for me to learn was to learn language and its syntax. Now my next training issue is to design my code heirarchy in such a way it is simple to maintain over time. One example I just encountered is below. It is in VBA for Excel but the concept extends to other languages too. ... | As a developer you will come across this situation all the time - I have a problem with two solutions. Both appear to solve the problem, both are of similar complexity, there is no obvious reason to choose one over the other (patterns, practices, personal preference, etc). Which should I do?
The problem with the quest... | I'm not terribly familiar with VBA, but at a glance it seems this syntax would be preferable in every way:
<pre><code>For ws in Worksheets
remove duplicates
append remaining data to separate workbook
Next ws
</code></pre>
For one thing, it seems quite readable to me.
For another, you're doing one loop, not tw... | https://softwareengineering.stackexchange.com |
22,441 | [
"https://stats.stackexchange.com/questions/22441",
"https://stats.stackexchange.com",
"https://stats.stackexchange.com/users/9042/"
] | I am trying to find a solution to compare two "goodness-of-fit chi-square" tests.
More precisely, I want to compare results from two independent experiments. In these experiments the authors used the goodness-of-fit chi-square to compare random guessing (expected frequencies) with observed frequencies. The two experime... | The very limited information you have is certainly a severe constraint! However, things aren't entirely hopeless.
Under the same assumptions that lead to the asymptotic $\chi^2$ distribution for the test statistic of the goodness-of-fit test of the same name, the test statistic under the alternative hypothesis has, a... | You could get the Cramer's V, which is interpretable as a correlation, convert it to a Fisher's Z, and then the confidence interval of that is straightforward (SE = 1/sqrt(n-3): Z ± se * 1.96). After you get the ends of the CI you can convert them back to r.
Have you considered putting all of your counts into a conti... | https://stats.stackexchange.com |
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