text stringlengths 1 1.11k | source dict |
|---|---|
quantum-mechanics, wavefunction, potential, schroedinger-equation, scattering
And in the same page,the wave correspond to A is called incident wave ,B reflected wave and F transmitted wave,the terminology is weird. There is no wave from the right. You're performing the analysis under the assumption that a wave is incident on the barrier from the left; as a result, there will be an incident component on the left $(A)$, a reflected component on the left $(B)$, and a transmitted component on the right $(F)$. | {
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"url": null
} |
lagrangian-formalism, field-theory, coordinate-systems, hamiltonian-formalism
Title: Why change of variables in the Hamiltonian give us the same physics while changes of variables in the Lagrangian does not? Suppose we have the Lagrangian density
$$L=\partial_\mu\phi\partial^\mu\phi-m^2\phi^2\tag 1$$
With $\phi$ a scalar field and $\pi=\frac{\partial L}{\partial \dot{\phi}}=2\dot{\phi}$ we can show that the Hamiltonian density $H$ is given by
$$H=\pi+\nabla \phi \cdot \nabla \phi+m^{2} \phi^2 \tag 2$$
Now suppose we make a change of variables $$\phi=\sin \eta \tag 3$$ we obtain
$$L(\phi)=L'(\eta)=\partial_\mu\eta\partial^\mu\eta\cos^2\eta-m^2\sin^2\eta$$
From $L'(\eta)$ we can construct the another Hamiltonian density
$$H'=\pi'+ \nabla\eta\cdot\nabla\eta\cos^2\eta+m^2\sin^2\eta \tag 4$$
where $\pi'=2\dot{\eta}\sin^2\eta$
Now if we make the substitution $(3)$ in $(2)$ we obtain
$$H(\phi)=H''(\eta)=\pi+ \nabla\eta\cdot\nabla\eta\cos^2\eta+m^2\sin^2\eta \tag 5$$
Comparing $(4)$ and $(5)$ we see that $H'\neq H''$ | {
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"url": null
} |
c++, hangman
if (pred(*first)) *result++ = *first;
for (Size i = 1; i < count && first != last; ++i)
{
if (pred(*first)) *result++ = *++first;
}
}
but it's basically a function that reads n inputs matching the predicate, and copies them to result.
But the way it's called:
auto begin = std::istream_iterator<std::string>(std::cin);
auto end = std::istream_iterator<std::string>();
copy_if_n(begin, end,
Max,
std::inserter(s, s.begin()),
[](const auto& str)
{
return std::regex_match(str, Letters);
});
It makes the whole thing seems overly complicated and feel like you forced yourself to use std::copy.
You could have done it much simpler:
do {
string str;
cin >> str;
if (str.length() > 0 && regex_match(str, Letters)) {
s.insert(str);
}
} while (s.size() < Max && !cin.fail()); | {
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And the radius is $2$ units.
let equation of circles are : $x^2+y^2-2x\pm2\alpha y=0$ [c=0; as circles pass through (0,0)] ; then $R=\sqrt{\alpha^2+1}=2$
• what does x=1 mean in the problem? Does it mean 1 unit of the x-axis? – Samama Fahim Mar 31 '13 at 15:24
• in the diagram, is any of the circle passing through the origin? – Samama Fahim Mar 31 '13 at 15:30
• @SamamaFahim x=1 is the equation of the vertical line . And both pass through origin.Origin is intersection of X-axis and Y-axis – ABC Mar 31 '13 at 15:37
• how did you know that x=1 is a vertical line? – Samama Fahim Mar 31 '13 at 15:46
• @SamamaFahim Okay,You need to study some basics of co-ordinate geometry. As equation is $x=1$ , does not depend on $y$ so it must be locus of those points which have x-coordinate =1 independent of y. So, it must be a vertical line (x=constant,y is varying) passing through (1,0). – ABC Mar 31 '13 at 15:49 | {
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"url": "https://math.stackexchange.com/questions/347344/circles-of-radius-2-passing-through-origin-with-centers-on-x-1"
} |
convolutional-neural-network, torch
Title: Unable to figure out nInputPlane in SpatialConvolution in torch? Documentaion for Spatial Convolution define it as
module = nn.SpatialConvolution(nInputPlane, nOutputPlane, kW, kH, [dW], [dH], [padW], [padH])
nInputPlane: The number of expected input planes in the image given into forward().
nOutputPlane: The number of output planes the convolution layer will produce.
I don't have any experience with torch but i guess i have used a similar function in keras
Convolution2D(64, 3, 3, border_mode='same', input_shape=(3, 256, 256))
which takes as input the shape of the image that is 256*256 in rgb.
I have read usage of Spatial Convolution in torch as below but unable to figure out what does the nInputPlane and nOutputPlane paramter correspond to?
local convLayer = nn.SpatialConvolutionMM(384, 384, 1, 1, 1, 1, 0, 0) | {
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"url": null
} |
Lemma $\$ Suppose $\;\rm D\subset\mathbb Z \;$ is closed under subtraction and that $\rm D$ contains a nonzero element.
Then $\rm D \:$ has a positive element and the least positive element of $\rm D$ divides every element of $\rm D\:$.
Proof $\rm\,\ \ 0 \ne d\in D \,\Rightarrow\, d-d = 0\in D\,\Rightarrow\, 0-d = -d\in D.\,$ Hence $\rm D$ contains a positive element. Let $\rm d$ be the least positive element in $\rm D$. Since $\rm\: d\,|\,n \!\iff\! d\,|\,{-}n,\,$ if $\rm\, c\in D$ is not divisible by $\rm d$ then we may assume that $\rm c$ is positive, and the least such element. But $\rm\, c-d\,$ is a positive element of $\rm D$ not divisible by $\rm d$ and smaller than $\rm c$, contra leastness of $\rm c$. So $\rm d$ divides every element of $\rm D.\$ QED | {
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"url": "https://math.stackexchange.com/questions/919681/square-root-of-2-irrational-alternative-proof"
} |
navigation, odometry, turtlebot, ros-electric
Title: Moving Turtlebot to a goal without a map
Hi there!
We're two newbies. We installed Ros Electric on a pc acer aspire 5740g running Ubuntu Lucid 10.04. Our task is to move Turtlebot giving vocal commands. We're doing it writing publishers and subscribers in c++.
We have a node which does the speech recognition, it publishes on a topic the identified word. When for example it publishes "advance" and "one", the turtlebot should move forward for one meter and then stop, waiting for new commands. We have to make the turtlebot do this without a map, only using odometry data.
Our problem is that turtlebot doesn't stop after it has reached the goal.
To give you an idea of what we're doing, here's part of the code:
geometry_msgs::PoseWithCovarianceStamped msg;
double pos_x,pos_y,pos_z,ori_x,ori_y,ori_z,ori_w;
void odomcallback(const geometry_msgs::PoseWithCovarianceStamped msg_turtlebot)
{
msg=msg_turtlebot;
pos_x=msg.pose.pose.position.x;
pos_y=msg.pose.pose.position.y; | {
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"tags": "navigation, odometry, turtlebot, ros-electric",
"url": null
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the... Means together, thus, correlation means the relationship between two variables in Python we! Corrcoef ( ) function correlation measures have been created ; the one in. Factors that lead to the relationships and it is a measure of correlation and negative correlation a linear equation +... Have been created ; the one used in this case is called the correlation..., Statistics II for Dummies, and there may be different factors that lead to the.!, Statistics II for Dummies you are required to calculate the coefficient of correlation and it is a measure correlation... relation '' degree & direction of the x and y statisticians use the Numpy corrcoef ( ).... By this calculator ( which is 2 ), and Probability for Dummies will continue to an. That do not meet a normal distribution continue to have an idea about the &. Relationships between variables, and there may be different factors that lead to the relationships %! In Excel by using the CORREL function or the Analysis Toolpak add-in | {
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"lm_q1_score": 0.9748211546419276,
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"lm_q2_score": 0.8354835371034368,
"openwebmath_perplexity": 689.2304979536979,
"openwebmath_score": 0.5549497008323669,
"tags": null,
"url": "http://hitterslog.com/french-vanilla-koxxba/how-to-calculate-correlation-d8250c"
} |
homework-and-exercises, scattering
$$
\frac{d}{dt}\frac{\partial L}{\partial \dot r} = \frac{\partial L}{\partial r} \implies \frac{d}{dt}(m\dot r) = -\frac{\partial}{\partial r}\left( \frac{1}{2}mr^2\dot\theta^2 + V(r) \right)
$$
$$
\frac{d}{dt}\frac{\partial L}{\partial\dot\theta} = \frac{\partial L}{\partial \theta} \implies \frac{d}{dt}\left(mr^2\dot\theta\right) = 0
$$
The second of these implies that the angular momentum $\ell = mr^2\dot\theta$ is constant. Or, rearranging, $\dot\theta = \ell/mr^2$. We use this to eliminate $\dot\theta$ from the radial equation of motion,
$$
m\ddot r =-\frac{\partial}{\partial r}\left(\frac{\ell^2}{2mr^2} + V(r)\right)
$$
This now looks just like Newton's equation of motion for 1-d motion in the "effective potential" $U(r) = \frac{\ell^2}{2mr^2} + V(r)$. In this 1-d picture, the particle's kinetic energy is $\frac{1}{2}m\dot r^2$, so the conservation of energy during the scattering can be expressed by the relationship
$$ E = \frac{1}{2}m\dot r^2 + U(r)$$ | {
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including sums, differences, double and half summary of trigonometric identities Use the fundamental trigonometric identities to evaluate trigonometric functions, simplify trigonometric expressions, and rewrite. In a right triangle with legs a and b and hypotenuse c, and angle α opposite side a, the trigonometric functions sine and cosine are defined as sinα = a/c, cosα = b/c. Here is a video explaining how you can simplify identities. The resulting equation can be solved for the sine squared term. It also contains the following identities: tangent identities, reciprocal identities, Pythagorean identities, periodic identities, even/odd identities, double angle identities, half angle identities, 2 Graph trigonometric functions polar equations and conic sections 3 Solve from MAT 188 at Pima County Community College In this page you will get the test of chapter 10 Trigonometric Identities Sum and Difference of Angles of FSC (Pre-engineering) and ICS. Techniques used in solving equations, | {
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"lm_q2_score": 0.8128673155708975,
"openwebmath_perplexity": 564.1065187435921,
"openwebmath_score": 0.8320470452308655,
"tags": null,
"url": "http://jimmec.com/fvh/how-are-sum-and-difference-identities-used-in-solving-trigonometric-equations.html"
} |
Notation: For $x,y \in \Bbb R$ let In$[x,y]=[x,y]\cup [y,x].$ That is, in the standard topology on $\Bbb R$ the set In$[x,y]$ is the closed interval from $x$ to $y$ (and vice-versa).
Let $S$ be open in the lower-limit topology. For $x,y\in S$ let $x\sim y \iff$ In$[x,y]\subset S.$ It is easily shown that
(i'). $\sim$ is an equivalence-relation on $S.$
(ii'). For $x\in S$ the equivalence-class $[x]_{\sim}=\{y\in S :y\sim x\}$ is a convex set of non-zero length.
(iii'). If $[x]_{\sim}$ is bounded above then it does not contain its sup, but if it is bounded below then it may or may not contain its inf .
The set $P$ of equivalence classes is a partition of $S$, so the equivalence-classes are pair-wise disjoint. Each equivalence class contains a rational, and the classes are pair-wise disjoint, so $P$ is finite or countably infinite.
And of course $S=\cup P.$
Observe that if $z=\sup \;[x]_{\sim}<\infty$ then $z\not \in S .$ | {
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"url": "https://math.stackexchange.com/questions/2708756/open-sets-with-respect-to-the-lower-limit-topology"
} |
ros2, message-filters
using namespace std::chrono_literals;
/* This example creates a subclass of Node and uses std::bind() to register a
* member function as a callback from the timer. */
class MinimalPublisher : public rclcpp::Node
{
public:
MinimalPublisher()
: Node("minimal_publisher"), count_(0)
{
publisher_ = this->create_publisher<std_msgs::msg::String>("topic2", 10);
timer_ = this->create_wall_timer(
1000ms, std::bind(&MinimalPublisher::timer_callback, this));
}
private:
void timer_callback()
{
auto message = std_msgs::msg::String();
message.data = "Hello, world! " + std::to_string(count_++);
RCLCPP_INFO(this->get_logger(), "Publishing: '%s'", message.data.c_str());
publisher_->publish(message);
}
rclcpp::TimerBase::SharedPtr timer_;
rclcpp::Publisher<std_msgs::msg::String>::SharedPtr publisher_;
size_t count_;
}; | {
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3
While Richard's answer is technically correct, just saying the result can be obtained using Ito's formula doesn't make the issue much clearer. So let me go into the microscopics of the issue. The Ito integral is defined in the following way. Suppose we divide the time interval $[0,t]$ into $n$ pieces with $t_i = i~dt$ where $dt=\frac{t}{n}$ then we define ...
3
I would not say there is no link to what you say but here would be my view. Intuitive explanation If you wait for a delay $h$ before exercising, you lose your exercise right between $t$ and $t+h$, this leads to a loss in value. Supermartingale property proof (to apply it in your case : $\phi_t=e^{-rt}(L-S_t)^+$) If we denote $\phi$ the obstacle, and ...
2 | {
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"lm_q2_score": 0.8397339716830605,
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"openwebmath_score": 0.9982936382293701,
"tags": null,
"url": "http://quant.stackexchange.com/tags/stochastic-calculus/hot?filter=year"
} |
deep-learning, keras, tensorflow, image-classification, data-science-model
# place the head FC model on top of the base model (this will become
# the actual model we will train)
model = Model(inputs=baseModel.input, outputs=headModel)
# loop over all layers in the base model and freeze them so they will
# *not* be updated during the first training process
for layer in baseModel.layers:
layer.trainable = False
# compile our model
print("[INFO] compiling model...")
opt = Adam(lr=INIT_LR, decay=INIT_LR / EPOCHS)
model.compile(loss="binary_crossentropy", optimizer=opt,
metrics=["accuracy"])
# train the head of the network
print("[INFO] training head...")
H = model.fit(
aug.flow(trainX, trainY, batch_size=BS),
steps_per_epoch=len(trainX) // BS,
validation_data=(testX, testY),
validation_steps=len(testX) // BS,
epochs=EPOCHS)
# make predictions on the testing set
print("[INFO] evaluating network...")
predIdxs = model.predict(testX, batch_size=BS) | {
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} |
python, performance, python-3.x, random
for col in lst_col:
blocks[col] = [a for a in blocks[col] if a[1] != point[1]]
for row in lst_row:
blocks[row] = [a for a in blocks[row] if a[0] != point[0]]
#Adjust the points to fit the grid they fall in
point = (point[0] + n * block[0], point[1] + n * block[1])
append(point)
return points | {
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} |
Is the matrix $A$ positive (negative) (semi-) definite?
Given, $$A = \begin{bmatrix} 2 &-1 & -1\\ -1&2 & -1\\ -1& -1& 2 \end{bmatrix}.$$
I want to see if the matrix $A$ positive (negative) (semi-) definite.
Define the quadratic form as $Q(x)=x'Ax$.
Let $x \in \mathbb{R}^{3}$, with $x \neq 0$.
So, $Q(x)=x'Ax = \begin{bmatrix} x_{1} &x_{2} &x_{3} \end{bmatrix} \begin{bmatrix} 2 &-1 & -1\\ -1&2 & -1\\ -1& -1& 2 \end{bmatrix} \begin{bmatrix} x_{1}\\x_{2} \\x_{3} \end{bmatrix}$.
After multiplying out the matrices I am left with $$Q(x) = 2(x_{1}^{2}+x_{2}^{2}+x_{3}^{2}-x_{1}x_{2} - x_{1}x_{3}-x_{2}x_{3}).$$
Not sure what I can do with this result. Any suggestions on how to proceed would be appreciated.
A simple way is to calculate all principle minors $A$ and if they are all positive, then $A$ is positive definite.
For example, $|A|_1=2>0$
$$|A|_2=\left|\begin{array}{}{\quad2 \quad-1\\ -1\quad 2} \end{array}\right|=3>0$$ Then calculate $|A|_3=|A|$. | {
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} |
quantum-field-theory, quantum-electrodynamics, renormalization, scattering-cross-section
Adding a virtual fermion: such graphs do not produce infrared divergences
Adding a virtual photon: if the photon is SOFT (i.e. low energetic), such graphs correspond to infrared divergences, and hence, those graphs are the graphs we wish to study. | {
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c++, object-oriented, playing-cards
What if I use my first and last name? This will cause player_name to be filled with my first name, and it will probably cause Invalid Input to be printed the first time handle_human_player() is called. To ensure you read whole lines of input, use std::getline():
std::string player_name;
std::cout << "Enter your name: ";
if (!std::getline(std::cin, player_name)) {
std::cerr << "Input failure\n";
return;
}
When you want to read numbers, you will have to convert the string containing the line you just read to a number, for example using std::stoi():
std::string line;
std::cout << "Enter number of players: ";
if (!std::getline(std::cin, line)) {
std::cerr << "Input failure\n";
return;
}
int no_of_players = std::stoi(line); | {
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} |
np-hardness, optimization, quantum-computing, time-complexity
The first one point is perhaps often elided over by start-up companies who are financially motivated to generate excitement for their quantum computers. The second point led recently to a couple of massive threads on Aaronson's blog. | {
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ros
Originally posted by Bogdar_ with karma: 136 on 2017-03-16
This answer was ACCEPTED on the original site
Post score: 1 | {
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# Probability: What is the probability of drawing items from containers?
1. Mar 5, 2014
### sanctifier
1. The problem statement, all variables and given/known data
There are 3 boxes containing some products of same type.
Box 1 contains 10 products and 3 of them are flawed.
Box 2 contains 15 products and 7 of them are flawed.
Box 3 contains 25 products and 5 of them are flawed.
Randomly choose one box from the 3 then draw one product from the chosen box, continue to draw one product from rest products in the chosen box, i. e., drew product will not be returned to the box.
Question 1 : What is the probability that the 1st drew product is a flawed one?
Question 2: What is the probability that the 1st drew product is a flawed one if we know the 2nd drew product is unflawed?
2. Relevant equations
Nothing special.
3. The attempt at a solution
$p= \frac{1}{3} \frac{3}{10} + \frac{1}{3} \frac{7}{15} + \frac{1}{3} \frac{5}{25}$ | {
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javascript, callback, vue.js
// This is a subject to a few more changing, maybe...
Object
.entries(chartData)
.forEach((entry) => {
Object.entries(entry[1]).forEach((dataItem) => {
datasets = datasets.map((e) => {
if (e.label === dataItem[0]) {
e.data.push(dataItem[1].median);
}
return e;
});
});
});
return datasets;
}
Update As @Gerrit0 suggested, Object.values(...) is a better option than Object.entities(...).map(...) (more concise and achieves exactly the same result). | {
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java, android
</LinearLayout> Variables
int width = 0;
int position = 0;
ArrayList<String> arr_string = new ArrayList<String>();
These variables should be private final and the ArrayList should be declared as List to allow easier switch to another List implementation.
private final int width = 0;
private final int position = 0;
private final List<String> arr_string = new ArrayList<String>();
XML
Considering the pattern of your XML files, you might want to create the layouts dynamically, with code, instead of using XML files.
I don't really see why you're wrapping all your inner LinearLayouts inside an outer LinearLayout in your layout_one-three.xml I think that you can remove
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" > | {
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graph-theory, graph-algorithms, graph-minor
Title: H-induced Containment problem In the paper "On Graph Contractions and Induced Minors" by Pim van't Hof et al. they showed that this problem is fixed parameter tractable in |VH| if G belongs to any non-trivial minor-closed graph class and H is a planar graph.
However, My failure to find a specific algorithm led me to ask the following question. | {
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self-study, equalization
Title: Constant modulus algorithm - performance poor? The question is based on a research article titled, "Novel Robust Blind Equalizer for QAM Signals
Using Iterative Weighted-Least-Mean-Square
Algorithm"
The Authors have proposed an equalization scheme for channel equalization for QAM symbols. The Authors in the last page, Table I present their results. The first column result is for Constant Modulus lagorithm given below:
5 (dB) 6.36 ; 10 (dB) 9.90 ;15 (dB) 15.12; 25 (dB) 18.0
with the plot
The Authors say that the values are in dB, but I don't undertstand why the SIR curve is increasing. In general, lesser the value of SIR, better is the perofrmance. But the curve shows the opposite. So, does CMA not work for QAM? | {
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javascript, algorithm, dom, ecmascript-6
// Loop through array, filter and loop thtough
_(array).filter(condition).forEach(callback);
Native isn't as different either:
// Loop through object and get length
Object.keys(obj).length
// Loop through array, filter and loop thtough
array.filter(condition).forEach(callback);
Anyways, maintainability aside...
Your API calls itself each, but tries to do N number of things. I suggest you name it verbosely if you want to keep the functionality. Something like forEachFilterByOptionalConditionAndReturnLength. That sounds about right.
Array.isArray(obj)
You claim that you can loop through any collection. However, your condition doesn't seem to take this into account. NodeList will not pass your isArray test and will fall in the object loop. However, NodeList is an array-like structure. It's best looped through like an array. Consider converting it into an array using slice.
fn(idx, val) | {
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coordination-compounds
And if yes, then which complex has the highest concentration? Yes, all those complexes from all those reactions will be present, and some more. Essentially Loong did all the mathematics in his answer to: Why is ligand substitution only partial with copper(II) ions and ammonia?
Let's shorten this a little bit and write the general reaction equation:
\begin{align}
\ce{[Cu(H2O)_{(7-n)}]^2+ + n NH3 &<=> [Cu(NH3)_n(H2O)_{(6-n)}]^2+ + n H2O};&
n&\in\{\mathbb{N}; 1,\dots,6\}
\end{align}
Therefore we can write the general equilibrium constant:
\begin{align}
K_n &=
\frac{{\left[ \ce{[Cu(NH3)_n(H2O)_{(6-n)}]^2+} \right]}}
{{\left[ \ce{[Cu(H2O)_{(7-n)}]^2+} \right]\left[ \ce{NH3} \right]^n}}\\
% K_\mathrm{B} &=
% \frac{{\left[ \ce{[Cu(NH3)6]^2+} \right]}}
% {{\left[ \ce{[Cu(H2O)6]^2+} \right]\left[ \ce{NH3} \right]^6}}
% &&= \prod_{n=1}^{6} K_n
\end{align} | {
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quantum-field-theory, supersymmetry, seiberg-witten-theory
Title: Seiberg duality and IR fixed point This question is related with Seiberg duality for $SU(N)$ gauge theory which states
a duality between electric theory, $SU(N_c)$ gauge theory with $N_f$ flavors is dual to its magnetic theory, $SU(N_f-N_c)$ theory with $N_f$ flavors with an additional gauge invaraint massless field.
This duality valid for conformal window $\frac{3N_c}{2} < N_f < 3N_c$
where both electric and magnetic theory have interacting IR-fixed
point.
Here i have question about $IR$ fixed points.
The beta function of electric theory(SQCD : $SU(N_c)$ gauge theory) is written as
\begin{align}
\beta(g) = -\frac{g^3}{16\pi^2} \frac{3N_c - N_f + N_f \gamma(g^2)}{1- N_c \frac{g^2}{8\pi^2}}
\end{align}
Thus we see $\beta>0$ for $N_f > 3 N_c$ for electric theory.
And using above results for magnetic theory, $\beta>0$ for $\frac{3N_c}{2} > N_f$. | {
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cosmology, space-expansion, big-bang, observable-universe
The radiation which bathed the universe at recombination time has since been stretched out in wavelength as the universe expanded and now resides in the microwave band of electromagnetic radiation. We call that "fossil radiation" the cosmic microwave background or CMB. This "afterglow" of the big bang is coming at us from all directions and its origin is behind all the most distant galaxies we can see today.
Neutrinos were generated in copious amounts before recombination, which means there are fossil neutrinos coming at us from times earlier than recombination. If we had some way to make images of that neutrino bath, we could then see farther back in time- but alas, even the best neutrino detectors we currently have are not sensitive enough to detect them. | {
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"tags": "cosmology, space-expansion, big-bang, observable-universe",
"url": null
} |
java, object-oriented, library
public void sendMessage(String to, String body) {
Message message = new Message(this.name, to, body);
Message response = this.postService.exchange(message);
if (this.hasOtherKingdomAllied(response)) {
this.allies.add(response.from);
}
}
private boolean hasOtherKingdomAllied(Message message) {
try {
Cipher cipher = Ciphers.cipher(Ciphers.SEASAR_CIPHER_TYPE, this.postService.getEmblemFor(message.from)
.length());
String decryptedMessage = cipher.decrypt(message.body);
return MessageResponses.POSITIVE_RESPONSE.equalsIgnoreCase(decryptedMessage);
} catch (NoSuchAlgorithmException e) {
return false;
}
} | {
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classification, nlp, word-embeddings, machine-translation
You need to use multilingual BERT
You need to prepare your data exactly as the tutorial says about how to set up your data, but use your own snippets in place of the sentence pairs | {
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# Continuous Exponential Growth And Decay Word Problems Worksheet | {
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} |
newtonian-mechanics, energy-conservation
the particles bounce back against each other in a perfectly elastic way. Think of a very elastic ball falling down: it will bounce. Conservation of energy holds so that the particles just flip their speed ($K\approx v^2$ so $K$ does not change), the kinetic energy is conserved and can be now used to transform it into potential energy as the particles move apart. Still the total energy $U+K$ is conserved.
the particles loose all of their energy and stop. Think of two cars colliding headfront. Again, this does not mean energy is lost: it just got transformed into heat and elastic deformations due to the collision (the two cars are now broken). Again, energy is conserved but the two particles lost it all, are immobile, and all the energy has flown somewhere else. For conservation of energy to be complete, you need to consider all source of energy (heat, elastic energy, vibrations of the atoms...) | {
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logic, recursion, type-theory, combinatory-logic, curry-howard
The Y combinator does not contradict this, for one key reason: it is not expressible in the simply-typed lambda calculus.
In fact, that was the whole point. Haskell Curry discovered the fixpoint combinator in the untyped lambda calculus, and used it to prove that the untyped lambda calculus is not a sound deduction system.
Interestingly, the type of Y corresponds to a logical paradox which isn't as well-known as it should be, called Curry's paradox. Consider this sentence: | {
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gazebo
Ones are free space, and zeros are walls.
Walls take up one cell (i.e. zeros at {0,1,1,1,1,0,1,1,0,1,1,1,1,0},).
My problem is that walls take up one cell in the matrix, but in Gazebo, they don't. So, if I want to move the robot from the top left corner, when the robot is at a door, in Gazebo it will be at the corridor. It will be at the corridor because, in gazebo, walls don't take up space, but in the matrix they take up one cell.
Do you have any suggestion about how to avoid this problem? (Maybe creating walls that take up one cell space in Gazebo)
Originally posted by VansFannel on Gazebo Answers with karma: 15 on 2019-07-02
Post score: 0
Model your walls using primitive geometries as models. Do not enter Building Editor.
Originally posted by kumpakri with karma: 755 on 2019-07-02
This answer was ACCEPTED on the original site
Post score: 1 | {
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finite-automata
The $\sigma$ should be set of the alphabet which is ranked $n$, how can a set of alphabet become a function?
Thank you. You're over-thinking it. It just says that, if $t_0$, ..., $t_{n-1}$ are in $T^0_\Sigma$ and $\sigma$ is a symbol in the alphabet $\Sigma_n$, then the string consisting of $\sigma$, followed by $($, followed by... is in $T^0_\Sigma$ | {
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newtonian-mechanics, forces, classical-mechanics, kinematics
Why is the acceleration only along horizontal component of tension force. It should be along the the net tension force (along the rope) The acceleration is always in the direction of the net force (Newton's Second Law). In your example, if you simply resolve all the forces in the vertical and horizontal directions, you can see why. | {
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python, design-patterns, library
class BinsKeepingContents(BinsKeepingSums):
def __init__(self, numbins: int):
super().__init__(numbins)
self.bins = [[] for _ in range(numbins)]
def add_item_to_bin(self, item: float, bin_index: int):
super().add_item_to_bin(item, bin_index)
self.bins[bin_index].append(item)
def result(self):
return self.bins
Now, I can write the algorithm only once, sending the desired Bins structure as parameter:
def greedy(bins: Bins, items: List[float]):
"""
Partition the given items using the greedy number partitioning algorithm.
Return the partition. | {
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quantum-mechanics, dirac-equation, time-evolution
Title: A question in Dirac article about Dirac equation about a sentence
Why it is said $W$ should be linear partial time derivative so that wave function could be determined by initial wave function? If the equation is not linear (say quadratic) in $\partial_t$, then one needs to know more about the initial condition than just the initial wavefunction.
As an example, in Newtonian dynamics, one needs to know both the initial position and the initial velocity, whereas in non-relativistic quantum mechanics one only needs the initial wavefunction (and not the initial "rate of change" of the initial wavefunction).
This is this property of the quantum dynamical mechanics that Dirac is trying to preserve when he introduces his equation. | {
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# Reparameterization Trick¶
Here we will understand the reparameterization trick used by Kingma and Welling (2014) to train their variational autoencoder.
Assume we have a normal distribution $q$ that is parameterized by $\theta$, specifically $q_{\theta}(x) = N(\theta,1)$. We want to solve the below problem $$\text{min}_{\theta} \quad E_q[x^2]$$ This is of course a rather silly problem and the optimal $\theta$ is obvious. We want to understand how the reparameterization trick helps in calculating the gradient of this objective $E_q[x^2]$.
One way to calculate $\nabla_{\theta} E_q[x^2]$ is as follows $$\nabla_{\theta} E_q[x^2] = \nabla_{\theta} \int q_{\theta}(x) x^2 dx = \int x^2 \nabla_{\theta} q_{\theta}(x) \frac{q_{\theta}(x)}{q_{\theta}(x)} dx = \int q_{\theta}(x) \nabla_{\theta} \log q_{\theta}(x) x^2 dx = E_q[x^2 \nabla_{\theta} \log q_{\theta}(x)]$$
For our example where $q_{\theta}(x) = N(\theta,1)$, this method gives $$\nabla_{\theta} E_q[x^2] = E_q[x^2 (x-\theta)]$$ | {
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optics, visible-light, reflection, refraction, geometric-optics
Title: Snell's law and Fermat's principle I have read this sentence on a book about the Snell's law of refraction, referring on a ray that passes from air ($n_1=1$) to glass ($n_2=1.55$):
"Snell's equation can be derived from Fermat's principle of least time. The path length in air has been increased relative to the path length in glass since the speed in air ($c/n_1$) is greater than the speed in glass ($c/n_2$). This is analogous to the situation of a lifeguard who must rescue a swimmer who is down the beach and out to sea. Since the guard can run faster then he can swim, he should not head directly for the swimmer but should run at an angle so that the distance covered on the beach is greater than the distance in the water and the total time can be minimized" | {
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"tags": "optics, visible-light, reflection, refraction, geometric-optics",
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java, unit-testing, fizzbuzz, rags-to-riches
Your test names are fairly generic. When a test fails the first thing you see is the test name. A good test name should be able to give you a good idea of what might be failing even before you see the test. Similarly, when someone is reading the test code for the first time, the shouldn't have to work to get a sense for the intent of the test.
Part of this issue is a result of your test cases being general categories. With this specific setup, try a number of things. Instead it is better to have many specific test cases instead of a few general test cases.
The biggest issue with doing this is that once one thing fails, no other assertions are executed. If there many things broken, you want to know about all of them. What you don't want is to find out that the thing you just fixed was only part of the problem and other things are still failing. | {
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To illustrate how the probability of $$B$$ and $$C$$ not sharing their birthday is affected once we know they don't share the same birthday with $$A$$ (how, indeed, that probability has gone down), consider what happens when we consider only three possible days that each of $$A$$, $$B$$, and $$C$$ can have their birthday.
First of all, the probability of $$B$$ and $$C$$ sharing their birthday not knowing anything about $$A$$ is $$\frac{1}{3}$$, and hence there is a $$\frac{2}{3}$$ probability that they don't share their birthday. | {
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that matrix is said to be a Symmetric Matrix. A square matrix A is said to be skew-symmetric if A T = −A. space? complex-valued square matrix A is said to be Hermitian if its A matrix P is said to be orthogonal if its columns are mutually orthogonal. View Square matrix.docx from BUS 135 at North South University. Matrix A is said to be skew symmetric if A^T = -A. Thus, a real-valued square | Determine k such that I-kA is idempotent. Means check if A ij = A T ij (Where 1 ≤ i ≤ m and 1 ≤ j ≤ n ) then the matrix is symmetric. 1 2 T A real square matrix $$A$$ is orthogonally diagonalizable if there exist an orthogonal matrix $$U$$ and a diagonal matrix $$D$$ such that $$A = UDU^\mathsf{T}$$. If A, B are square matrices of same order and B is a skew-symmetric matrix, show that A’ BA is skew symmetric. (1g) E ij has a 1 in the (i,j) position and zeros in all other positions. Uploaded By sallin9. & Determinants are definedonly for square matrices.If the determinant of a matrix is 0, the | {
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"url": "http://beta.raacked.com/the-honey-hzr/o92ez.php?eccfbe=a-square-matrix-a-is-said-to-be-symmetric-if"
} |
php, mvc, url-routing, google-maps, crud
Consider not placing DB credentials in code if feasible (i.e. inject them into environment upon environment start up.
Your $config array is problematic in that it is mutable. Typically application configuration should not be mutable at run time. Consider sticking with constants or using a class with constants that are statically accessible.
You have a reasonable start to a framework of your own. I would encourage you to think about how to better decouple application-specific configuration from the basic workings of the framework. This would allow you to better leverage this code on future projects/applications. For example, consider moving the route definitions into configuration. Be more consistent in how you display error pages relative to configured pages. You should be able to supply your own templates for these error pages and not have the layout so tightly coupled to the framework portion of the application. | {
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c#
foreach (var teamLeader in teamLeaders)
{
EmpGuid.Add(teamLeader.EmpGuid);
}
parameters = ToDataTable(EmpGuid);
}
But I need to add more checkboxes. For foreach checkbox I will add to my form I need to add it to each conditional, and at the final of the day I will get very long code. Is there another way to do this? It's not completely clear from the code, but assuming your intent is to display the combination of all selected sets, or the result of a separate list box if no sets are selected, then you can do it with one check per set.
Assuming EmpGuid is a List or similar that starts out empty (if not, modify as appropriate), and using some Linq to clean it up:
if(chkProjectTechs.Checked)
{
EmpGuid.AddRange(projectTechnicians.Select(x => x.EmpGuid));
}
if(chkTeamLeader.Checked)
{
EmpGuid.AddRange(teamLeaders.Select(x => x.EmpGuid));
}
// Other cases here ... | {
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redox
Second method (basic solution). Balancing the redox half-equation from $\ce{CrO4^{2-}}$ to $\ce{Cr^{3+}}$ without $\ce{H+}$ is not so easy. Because the $4$ Oxygen atoms of the chromate ion are of course transformed into $\ce{4OH-}$ ions, provided enough $\ce{H}$ are available. So this requires enough $\ce{H2O}$ on the left-hand-side to compensate for the $\ce{4 H}$ atoms included in these $\ce{4 OH-}$ : $\ce{2 H2O}$. But these $\ce{2 H2O}$ molecules bring new oxygen atoms. It is not obvious to see that, at the end, $\ce{4 H2O}$ (and not $2$) have to be added on the left-hand side. The final half-equation is :$$\ce{CrO4^{2-} + 4 H2O + 3 e- -> Cr^{3+} + 8 OH-} \tag{4}$$ This is equal to $(3)$. But it not so easy to obtain.
Final remarks. 1. Whatever the method used, it may be useful to state that the $\ce{Cr^{3+}}$ ion does not exist and makes a precipitate in basic solution so that the final equation should be written $$\ce{CrO4^{2-} + 4 H2O + 3 e- -> Cr(OH)3 + 5 OH-} \tag{5}$$ | {
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molecular-biology, senescence
This paper sees sir2.1 expression levels as an oversimplification of the causes of longevity. When they create crosses of the sir2.1 OE strain with wildtype, you can see the Outcross, which is verified to have a high level of sir2 expressed no longer has an extraordinary lifespan.
This can be seen in Figure 1. http://www.nature.com/nature/journal/v477/n7365/fig_tab/nature10296_F1.html
So this paper is now asking, if sir2 levels do not convey the information that creates an extended lifespan, then what does? It must be some modulation of some protein that sir2 affects. They implies that the actual cause of the lifespan increase may have been a mutation somewhere else in the organism.
"However, longevity was not suppressed by sir-2.1 RNA interference (RNAi) ... indicating causation by factors other than sir-2.1, either on mDp4 or elsewhere in the genome."
"This implies that lifespan extension is due to transgene-linked genetic effects other than the overexpression of dSir2." | {
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c#, entity-framework, automapper
The name of this product (so far) is EntityJustWorks. I have kept all these classes under the namespace EntityJustWorks.SQL, because these are all (more or less) SQL specific and I think that I may want to add another library that deals with a different repository. Does this seem like a sound naming convention? Would this do good to hide behind an 'live record'? Again I welcome all and any criticisms/comments.
If you would like to go straight to the code download, you can access my GitHub. I also keep a copy of my code, as well as comments and explanations of certain important sections on my C# programming blog.
namespace EntityJustWorks.SQL
{
public static class Convert
{
/// <summary>
/// Generates a C# class code file from a Database given an SQL connection string and table name.
/// </summary>
public static string SQLToCSharp(string ConnectionString, string TableName)
{ | {
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quantum-mechanics, quantum-information
Title: Is there a limit on the maximum rate of change of the position expectation value in quantum mechanics to be no greater than the speed of light? Suppose a particle, constrained to the $x$ axis, is measured at $t_0$ to be at position eigenstate $x = 0$.
Assume for all $t \gt t_0$, some external potential acts on the particle.
Nevertheless, at $t_1 \gt t_0$, the support of its position wave function must be an interval no longer than $[-c(t_1 - t_0), c(t_1 - t_0)]$ in order to satisfy special relativity.
(Here, a position wave function $\psi$ is such that $\psi \psi^*$ is the position probability density.)
Further, suppose:
At $t_1$, the position expectation value is $-c(t_1 - t_0)\lt x_{e_1} \lt c(t_1 - t_0)$
At $t_2 \gt t_1 $ the position expectation value is $-c(t_1 - t_0) \lt x_{e_2} \lt c(t_1 - t_0)$ and $x_{e_2} \ne x_{e_1}$
Also, assume there is no position measurement, after the one at $t_0$, until sometime after $t_2$. | {
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fourier-transform, frequency-spectrum, dft
In circular convolution, multiplying FT's coefficients exactly corresponds to time-domain convolution, but not DFT's; for DFT one must pad, which changes the coefficients. So in this sense, the interpretation of DFT coefficients changes with the periodicity assumption. | {
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thermodynamics, thermal-radiation, photon-emission
Title: What determines if a lamp produces emission or blackbody spectra? If we take a lamp containing hydrogen gas and heat it up (gas-discharge lamp), it produces hydrogen's emission spectrum. Why doesn't it produce a blackbody spectrum? After all, the gas has some temperature, and that allows for a blackbody spectrum.
Similarly, why does an incandescent light bulb (which has a tungsten filament within) yield a blackbody spectrum when heated, as opposed to tungsten's emission spectrum? To be a blackbody a source must be in thermal equilibrium and be capable of absorbing all radiation that is incident upon it.
The hydrogen discharge lamp can do the former - the hydrogen energy levels are populated according to the Boltzmann factors$^1$ and there may even be a little ionisation. However, it cannot do the latter - it could absorb radiation at the discrete frequencies governed by the hydrogen energy levels, but is otherwise quite transparent (by design). | {
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gas-laws, heat
Hydrogen and oxygen can be obtained via simple electrolysis.
$$\ce{2H2O + Energy -> 2H2 + O2}$$
and combined back as
$$\ce{2H2 + O2 -> 2H2O + Energy}$$
It might be worth noting that for all practical purposes, the energy you use to split hydrogen and oxygen will always be greater than what you can get by combining them back (like what happens in every combustion engine, humans have ever created).
If you are planning to develop an actual application, there are many precautions that you would need to consider, the most important of which would be back-fire protection (a common problem with gas based welding), so that the flame doesn’t reach back into the gas tank, which of course will explode.
So goes without saying, but you might want to adopt some precautionary measures if you do use it in any practical application. Temperatures this high can seriously hurt a person even if the contact was for some milliseconds. It can also damage other materials if the flame is directed at them. | {
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lie-algebra
\end{equation}
\begin{equation}
\tilde{J}_1=\frac{2r\sin\tau}{\sqrt{1+r^2}}\partial_\tau-2\sqrt{1+r^2}\cos\tau\partial_r+\frac{2\sin\tau}{\sqrt{1+r^2}}\partial_\varphi
\end{equation}
\begin{equation}
\tilde{J}_2=-\frac{2r\cos\tau}{\sqrt{1+r^2}}\partial_\tau-2\sqrt{1+r^2}\sin\tau\partial_r-\frac{2\cos\tau}{\sqrt{1+r^2}}\partial_\varphi
\end{equation}
with algebra that satisfies
\begin{equation}
[\tilde{J}_0,\tilde{J}_1]=-2\tilde{J}_2,\quad [\tilde{J}_0,\tilde{J}_2]=2\tilde{J}_1,\quad [\tilde{J}_1,\tilde{J}_2]=2\tilde{J}_0
\end{equation}
and Jacobi identity is also satisfied.
Now, my question is, since this is $SL(2,\mathbb{R})$ group, shouldn't the algebra be the same? That is, shouldn't Lie brackets be identical in the first and second case? Why is there a difference?
In one case I have $[X,Y]=2Y$, and in other $[X,Y]=-2Z$ basically. Is this because of how we defined the generators? | {
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c++, recursion, template, c++20, constrained-templates
// One last sanity check.
if constexpr( is_sized<Container<T, N>> && is_sized<recursive_invoke_result_t<F, Container<T, N>>> )
{
assert( output.size() == input.size() );
}
return output;
}
}
/* recursive_sum_all template function performs summation operation on input container exhaustively
*/
template<class T> requires is_summable<T>
auto recursive_sum_all(const T& input)
{
return input;
}
template<std::ranges::input_range T>
auto recursive_sum_all(const T inputArray)
{
typedef typename std::iterator_traits<typename T::iterator>::value_type
value_type;
decltype(recursive_sum_all(std::declval<value_type &&>())) sun_output{};
for (auto& element : inputArray)
{
sun_output += recursive_sum_all(element);
}
return sun_output;
} | {
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Each set $F_i$ is compact since it is closed in $Z$. The intersection of finitely many $F_i$ is also compact. Thus the $\cap G$ in the definition of $Y$ in the above claim is compact. There can be only countably many $\cap G$ in the definition of $Y$. Thus $Y$ is a $\sigma$-compact space that is covered by the open cover $\mathcal{U}$. Choose a countable $\mathcal{V} \subset \mathcal{U}$ such that $\mathcal{V}$ covers $Y$. Then $\mathcal{V}$ is a cover of $X$ too. This completes the proof that $X$ is Lindelof.
$\text{ }$
Proof of Theorem 4
Recall that $Z=\prod_{i=1}^\infty Z_i$ and that $X=\prod_{i=1}^\infty C_i$. Each $Z_i$ is the one-point compactification of $C_i$, which is the topological sum of the disjoint compact spaces $C_{i,1},C_{i,2},\cdots$.
For integers $i,j \ge 1$, define $K_{i,j}=C_{i,1} \oplus C_{i,2} \oplus \cdots \oplus C_{i,j}$. For integers $n,j \ge 1$, define the product $F_{n,j}$ as follows: | {
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In this example, we set column B to contain the amount currently spent, and column C is the percentage by which to reduce that amount. In Australia itâs called GST (General Services Tax). Then you copy this formula to the other cells with the fill-handle. Format the result to a percentage. To Calculate a percentage increase or increase a number by a specified percentage, simply multiply that number by 1 plus the percentage increase. Or: Assuming the estimated number is the "baseline" value and actual is a "new" value, the formulas take this shape: To increase a number by a percentage amount, multiply the original amount by 1+ the percent of increase. 2. 2. When finding the percentage difference and your result is a negative value, know that your answer is âpercentage decreaseâ. The mathematical formula for calculating percentage is as follows: (part / whole) * 100. A value returned from this formula is a percentage and often appears as a fraction. To see the true percentage in | {
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python, performance, python-2.x
With this the calling code becomes:
if __name__ == '__main__':
new_events = read_events(PATH_SOPHOS_TO_CUSTOMER, MATCH_LOG, NO_MATCH_LOG)
process_and_filter(new_events)
Note that Python's official style-guide, PEP8, recommends using ALL_CAPS for global constants. | {
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c++, error-handling
enum class BreakErrorCode {
FAILED_INIT_BREAKS = 1,
FAILED_TO_LINK_BREAKS = 2,
};
class BreakError : public std::system_error {
using Base = std::system_error;
public:
BreakErrorCode appErrorCode() const {
return static_cast<BreakErrorCode>(code().value());
}
explicit BreakError(const BreakErrorCode code)
: Base{(int) code, app_error_category()} {
}
BreakError(const BreakErrorCode code, const std::string &description)
: Base{(int) code, app_error_category(), description} {
}
};
enum class EngineErrorCode {
FAILED_INIT_ENGINE = 101,
MOTHER_BOARD_FAILED_LINKING = 102,
};
class EngineError : public std::system_error {
using Base = std::system_error;
public:
EngineErrorCode appErrorCode() const {
return static_cast<EngineErrorCode>(code().value());
} | {
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python
def import_data():
count=-1
samples=[]
mega_list=[]
total_concentrations=[]
per_line_1=[]
per_line_2=[]
per_line_3=[]
per_line_4=[]
per_line_5=[]
per_line_6=[]
per_line_7=[]
per_line_8=[]
per_line_9=[]
temp_concentrations_1=[]
temp_concentrations_2=[]
temp_concentrations_3=[]
temp_concentrations_4=[]
temp_concentrations_5=[]
temp_concentrations_6=[]
temp_concentrations_7=[]
temp_concentrations_8=[]
temp_concentrations_9=[]
with open('scaled_uncertanty_fits.txt') as data_file:
for lines in data_file:
line=lines.split(',')
sample_names=(line[0]).strip()
if sample_names in sample_list2:
samples.append(sample_names)
count+=1
if re.search('Open-Closed',sample_names) is not None and samples[count] == 'WT_2017':
per_line_temp,concentration=filter_data(line) | {
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general-relativity, cosmology, soft-question, observable-universe
In other words, the region that you travelled to might have its own event horizon, but that doesn't matter. What matters is whether or not you are still inside the event horizon of the Earth. If you are, then the Earth will receive the same information as you, and before you can make it back. If you aren't, then you can no longer communicate with the Earth, let alone travel back.
A final word of caution. A different region of space doesn't necessarily have a different event horizon. The FLRW metric is an idealization, and only valid on large scales. A region that is e.g. 100 light years away is gravitationally bound to us, and in the Standard $\Lambda$CDM model it will remain gravitationally bound. Since all observers in a bound structure can send signals to each other, they all share the same cosmological event horizon. | {
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php, mysql, classes, object-oriented
}
}
}
manageReports.class.php
include('filterReports.class.php');
/*
* As an extension of the previous class 'filterReports', if a desired report has
* not been found, we will create and save it.
*/
class manageReports extends filterReports
{
public $newReport;
private $dbConfig = array();
private $con;
private function dbParams() // This should all probably go somewhere else, but I haven't decided where just yet
{
$this->dbConfig = array(
'host' => 'hostname',
'user' => 'username',
'pass' => 'password',
'name' => 'database',
);
$this->con = mysql_connect(
$this->dbConfig['host'],
$this->dbConfig['user'],
$this->dbConfig['pass']
) or die('MySQL Error: ' . mysql_errno() . ' - ' . mysql_error());
}
private function createDailyOrdersReport() // Collect data and build the report body
{ | {
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#### MIP vs CP formulation
In the MIP formulation we used a binary representation of the decision variables $$x_{i,c}$$. If we would use a Constraint Programming solver (or an SMT Solver), we can can use integer variables $$x_i$$ directly.
Binary MIP formulationInteger CP formulation
\large{\begin{align}\min\>&0\\& x_{i,c} + x_{i+k,c} + x_{i+2k,c} \le 2 && \forall i+2k \le n\>\forall c \\ & \sum_c x_{i,c}=1 && \forall i\\ & x_{i,c} \in \{0,1\} \end{align}} \large{\begin{align} &x_{i} \ne x_{i+k} \vee x_{i+k} \ne x_{i+2k} && \forall i+2k \le n\\ & x_i \in \{1,\dots,nc\} \end{align} }
#### Python/Z3 version
This is to illustrate the integer CP formulation. Indexing in Python starts at 0 so we have to slightly adapt the model for this:
from z3 import *
n = 26
nc = 3
# integer variables X[i]
X = [ Int('x%s' % i ) for i in range(n) ] | {
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dna
Its difficult to study the effect of low levels of radiation. The lower the levels of radiation we are asking about, the longer you will have to wait to see if there is an effect. If 10% more people get cancer, you have a very real concern that some of these folks might have done something else, like sunbathe or live in a poorly ventilated basement for too long.
The real question is, what is significant? I once saw a 60 minutes segment where a dermatologist said that she simply never directly exposes her skin to direct sunlight. I'm betting she never got a melanoma. She carried a parasol and wore light gloves outdoors. (sorry I can't find the link) She was at least in her 50s and she had the skin of a teenager. I still go out in the sun. I assume my risk of melanoma is 5-10 times more than hers was (this was a pretty old broadcast). (mine is 0.03% in the next 5 years btw). Its just not worth it to me. | {
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Lecture 7 - Assumptions in the Method of Least Squares . Unlike interpolation, it does not require the fitted function to intersect each point. ALGLIB package supports nonlinear fitting by user-defined functions using Levenberg-Marquardt optimizer. Least Squares Estimates of 0 and 1 Simple linear regression involves the model Y^ = YjX = 0 + 1X: This document derives the least squares estimates of 0 and 1. New evidence, both documentary and statistical, is discussed, and an attempt is made to evaluate Gauss's claim. You will not be held responsible for this derivation. Loading... Unsubscribe from UMBCChemistry? General Topology; Group Theory; Real Analysis; Math Results And Formulas; Math Symbols; Curve Fitting and Method of Least Squares. It is a method very widely used in statistics. The most famous priority dispute in the history of statistics is that between Gauss and Legendre, over the discovery of the method of least squares. Linear least squares regression is by far the most | {
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"openwebmath_perplexity": 684.8661110582966,
"openwebmath_score": 0.49459317326545715,
"tags": null,
"url": "http://www.lmat-d.net/munchkin-quacked-pgzej/page.php?id=d53ff6-method-of-least-squares-statistics"
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deep-learning, reinforcement-learning, q-learning, robotics
In either case, one thing that should be noted is that you give your robotic arm enough time to actually perform the action that the agent selected. If not you will see your robot "jitter" back and forth quickly as your agent selects actions randomly. This is bad for a few reasons but most importantly because it might break your servos. To overcome this issue, give each action a little more time to be "actualized" by your robot. This can either come in the form of adding a delay in your code while your servos do "the thing" or by using an "iterations since last action update" counter to get a new action from the agent after a certain number of iterations. Not only is this better for your hardware, this also leads to better exploration of your state space as your agent can move through the state space encountering similar states more frequently. | {
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land-surface-models, validation
Title: Pertinence for a formulae similar of the RMSE to measure the meteorologic forcing impact on the variability on a model output I want to validate a model and compare several parameterizations. I have some observations so I calculated the RMSE for each parameterization with the best meteorological forcing.
However I want to nuance with the variability of the forcing. I suppose that more the forcing has an impact on outputs in its range of uncertainties, less the parameterization explains the amelioration of the RMSE.
In my case, I have 5 forcing files and 2 different parameterizations, the output $Y$ is a time series. I name $Y_{ij}(t)$ each output with the forcing $i$ and the param $j$
and I name the mean of $Y_{ij}(t)$ for each time step between all the forcing with the parameterization j as $\bar{Y_j}(t)$ and the time series of the observation is $y(t)$
I want to compare the RMSE with the following formulae (where I replace $y(t)$ by $\bar{Y_j}(t)$): | {
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Regarding the interpretation of the matrices: Let $$X = \left(\begin{array}{c} 1 \\ x \\ \vdots \\ x^n \end{array}\right) \qquad \textrm{and}\qquad A = \left(\begin{array}{c} a_0 \\ a_1 \\ \vdots \\ a_n \end{array}\right)$$ so $$X^T A = \sum_{k=0}^n a_k x^k.$$ (I've written $X^T A$ instead of the preferred $A^T X$ to agree with your notation and avoid things like $(M^{-1})^T$.) Then $$\begin{eqnarray*} X^T A &=& X^T M M^{-1} A \\ &=& {X'}^T A' \end{eqnarray*}$$ where $X' = M^T X$ is the new basis and $A' = M^{-1} A$ are the coefficients in the new basis. This interpretation holds for any invertible transformation $M$. The formalism can be generalized in a straightforward way to transformations between any two bases of polynomials. | {
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fft, discrete-signals, bandpass
An alternative would be to use a symmetric FIR filter. These filters do have linear phase, so it will delay all frequency components by an equal number of samples (the delay $D$ is equal to half of the filter order, so if you have $N$ total coefficients, the delay is $\frac{N-1}{2}$ samples). If you did this, then you could accomplish what you want by doing the following: | {
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mathematical-physics, probability, definition
Also, I read through this post, but it fails to answer my question. To paraphrase Littlewood, what can we say about the rate of convergence? This is the exact reason why we do statistical hypothesis confidence testing. In essence, the confidence interval we get from this test is a quantitative measure of "how far we've converged". For example, consider an experiment to test whether a coin is imbalanced or not. Our null hypothesis is that it is not: in symbols, our hypothesis is ${\rm Pr}(H) = \frac{1}{2}$: the probability of a head is a half. | {
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全文文献 工具书 数字 学术定义 翻译助手 学术趋势 更多
total completion time 的翻译结果: 查询用时：0.009秒
在分类学科中查询 所有学科 数学 工业通用技术及设备 自动化技术 更多类别查询
历史查询 | {
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"url": "http://dict.cnki.net/h_52281867000.html"
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thermodynamics, freezing, nucleation
Title: Explanation of the effect of nucleation sites on various processes It is common knowledge that water can be cooled and superheated in the absence of nucleation sites. Similarly, the well-known explosion of carbonated drinks due to the dropping of mentos is also explained by nucleation sites causing it.
What is the principle behind such nucleation sites? Why do such sites create rapid freezing/evaporation? While many sources mention that nucleation sites are the reason for such phenomena, very few of them actually explain why they cause these processes. the equations for phase-change phenomena generally assume that nuclei are present. this works in theory but in practice the absence of nuclei will seriously skew the real-world results, throwing experiment and theory apart. this is true for liquid-vapor, vapor-liquid, and liquid-solid phase changes.
Here is why nucleation sites work: | {
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pressure, fluid-statics, elasticity, stress-strain
Title: Contradiction of Bulk's Modulus and Pressure exerted by a static liquid My question is about a scenario where a certain amount of air is passed through water. Now, this air will form a bubble and due to the buoyant force acting on it, it will rise.
We know that the pressure exerted by a liquid at a certain distance 'h' from the free surface is ρgh where ρ is the density of the liquid. By this formula, we can predict that our bubble will increase in volume. Because when it rises , the pressure exerted on the bubble decreases, thus allowing it to increase in volume.
Now, we know that Bulk's modulus of elasticity = Volume stress / Volume strain. Volume stress, in our case, will be ΔP, where ΔP is the difference between the total pressure exerted on the bubble and the pressure exerted by the bubble. Volume strain will be -(ΔV)/V.
∴Bulk's Modulus of Elasticity = ΔP* V/-(ΔV)
Rearranging we get, ΔV = -ΔP* V/Bulk's Modulus of Elasticity | {
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time-series
Title: ARIMAX v. ARX Time Series Modeling I need to build a time series model with explanatory variables, and ARIMAX seems to be the one that comes up most frequently in practice, based on my survey of related work.
I know ARX solves a similar problem, but I'm having trouble wrapping my mind around the practical differences in what an ARX representation of my data would have compared with an ARIMAX approach.
I know ARX lacks the moving average component, but I'm curious whether anyone can point me toward some best practice for choosing one approach over the other.
Are there certain characteristics in my data I should look for to make an informed decision? Yes, there are characteristics. You can use a correlogram to inform you as to the error structure in your data. That will tell you whether or not your data needs to account for AR and/or MA terms. Also check for unit roots to tell you whether you need to difference the time series. | {
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terminology, programming-languages, logic, functional-programming, simulation
Title: Does the callback concept of programming have any basis in computer science? Although I seriously code with computer languages in general since 2010 and as an amateur programmer with programming languages in particular since 2015 (primarily Bash and JavaScript imperative scripts) and codes I wrote are scattered through my Stack Exchange accounts, as in my Code Review SE account,
I think I still misunderstand what a Callback is;
I feel that the term itself might be misleading, as I understand that callback functions doesn't "call back" anything, but rather "called back" as a reaction to a condition (event).
I understand the alternative term Callafter as significantly controversial between programmers, so I stay with "Callback" or its semantic siblings;
Any Stack Exchange session I read about "Callback" contained answers that I either recognized as contradicting or controversial by other programmers commenting in comments.
My question | {
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piece covers the very basics of set theory notation, operations & visual representations extensively. Set Notation. Set notation and Venn diagrams questions. The guide you are now reading is a “legend” to how we notate drum and percussion parts when we engrave music at Audio Graffiti. Thankfully, there is a faster way. The following list documents some of the most notable symbols in set theory, along each symbol’s usage and meaning. Also, check the set symbols here.. Under Equation Tools , on the Design tab, in the Symbols group, click the More arrow. 8 February 2019 OSU CSE 1. Topics you will need to know in order to pass the quiz include sets, subsets, and elements. Probability and statistics symbols table and definitions - expectation, variance, standard deviation, distribution, probability function, conditional probability, covariance, correlation Sets. Set notation. The table below lists all of the necessary symbols for compact set notation. Basic set operations. Note that it's | {
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newtonian-mechanics, newtonian-gravity, acceleration
Title: Why didn't I beat the avalanche? Yesterday, while skiing out of bounds on the south west canyons of Mt. Hood, I experienced a small and extremely mild quake. This, combined with the melting conditions caused an extremely small avalanche in the canyon region we where in.
This was extremely mild in the spectrum of what is shown on TV or from what I've seen in other videos. A snow field of a bout 100 sq.m, shifted about 100 m down hill. And while mild, this was still my first ever experience in this type of situation. | {
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gazebo
Originally posted by scpeters with karma: 2861 on 2014-04-24
This answer was ACCEPTED on the original site
Post score: 0
Original comments
Comment by gunnar on 2014-04-29:
Ok, thanks for your help! It seems to be working now. I have the models in the folder by cloning them. It must have been a combination of internet error on the first run and some other problem that must have resolved itself after rebuilding. | {
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java, stack
System.out.println("1 pop(): ");
ds.pop();
System.out.println("Min till now: " + ds.findMin());
System.out.println("Max till now: " + ds.findMax());
}
} Your MyDS class has the right idea, in general.
Special values like -1, Integer.MIN_VALUE, and Integer.MAX_VALUE make me suspicious. All of those special values denote what I consider to be error cases. Using special cases that might also be valid data is a dangerous habit that can lead to bugs. Instead of those special numbers, it would be better to throw exceptions — probably NoSuchElementException. You should also offer a size() and/or an isEmpty() method so that users of your data structure can proactively avoid encountering the exception. | {
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dna, dna-sequencing
Title: What DNA has the most info for getting a person's likeness? I understand that DNA can come from hair but also from other places.
Let's suppose a person gets their DNA mapped by a company (there are some companies claiming to offer analysis of DNA.. e.g. maybe $200 and maybe some may send the DNA on a DVD)
I understand from this link that human DNA should fit on a DVD
https://stackoverflow.com/questions/8954571/how-much-memory-would-be-required-to-store-human-dna
Would it be possible to get a person's likeness.. if not now, then in future, based on the DNA I might be able to get sent to me digitally.
And presumably the DNA of a 28 year old would be the most ideal for getting (in a computer program) the likeness/image of that person at 28 - the age the DNA was taken?
I hear of the cost of sequencing the human genome to be millions or billions.. Is that more about scientists figuring out what the DNA does, rather than capturing it all? | {
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cc.complexity-theory, graph-theory, np-hardness, reductions
$k$ copies of $c$, with the same neighborhood (so now we have a graph on $\{c_1, \dots, c_{k+1}\} \cup D$). We now search for a feedback vertex set. If I'm not mistaken, instance of feedback vertex set thus created has a solution of size $k$ iff our graph had a solution of size $k$ to our problem. | {
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c#, algorithm
{
seatArray = seatTwoPerson(seatArray, 0, maxCol, directionX, 0, maxRow, 1);
seatArray = seatTwoPerson(seatArray, 0, maxCol, directionX, 0, maxRow, 1);
seatArray = seatTwoPerson(seatArray, 0, maxCol, directionX, 0, maxRow, 1);
}
else
{
seatArray = seatThreePerson(seatArray, 0, maxCol, directionX, 0, maxRow, 1);
seatArray = seatThreePerson(seatArray, 0, maxCol, directionX, 0, maxRow, 1);
}
return seatArray;
}
public List<SelectListItem> populatePartySizeDDL()
{
List<SelectListItem> items = new List<SelectListItem>();
items.Add(new SelectListItem() { Text = "1", Value = "1", });
items.Add(new SelectListItem() { Text = "2", Value = "2" });
items.Add(new SelectListItem() { Text = "3", Value = "3" }); | {
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python, beginner, algorithm
All in all, your final program looks like this:
alphabet = 'abcdefghijklmnopqrstuvwxyz'
def decrypt(string: str) -> str:
output = ''
spaces = 0
for index, character in enumerate(string):
if character == " ":
output += " "
spaces += 1
continue
position = (index + 1) + (alphabet.index(character) + 1) - len(alphabet)
if position > len(alphabet):
position %= len(alphabet)
output += alphabet[position - 1 - spaces]
return output
word = input("Please enter the word to be decrypted: ").lower()
output = decrypt(word)
print(f"The word '{word}' decrypted is '{output}'")
We use spaces to shift the index back for every space we've encountered. | {
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c#, beginner, multithreading, comparative-review, bitwise
And the StateChanged event like this:
public delegate void LightCommunicationStateChanged(LightCommunicationStateMachine Sender, LightCommunicationState OldState, LightCommunicationState NewState);
public event LightCommunicationStateChanged StateChanged; Don't reinvent the wheel: use EventArgs
The StateChanged event isn't compliant with established C# conventions for creating events.
public delegate void LightCommunicationStateChanged(LightCommunicationStateMachine Sender, LightCommunicationState OldState, LightCommunicationState NewState);
public event LightCommunicationStateChanged StateChanged;
That is non-standard. C# conventions recommend using an EventHandler<T> delegate, where T is a type derived from System.EventArgs - the type could be as simple as this:
public class StateChangedEventArgs : EventArgs
{
public StateChangedEventArgs(LightCommunicationState oldState, LightCommunicationState newState)
{
_oldState = oldState;
_newState = newState;
} | {
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optimization, coffeescript
# $("<span rel='tooltip' title='Started Ranking' class='today'> <b>new</b> </span>").addClass("sortboxnew").css(css).appendTo(row1)
if a > b && b > 0
$("<span rel='tooltip' title='Decreased' class='yesterday'> <b>#{a - b}</b> </span>").addClass(sortboxarrowdown).css(css).appendTo(changes)
else if a > b && b is 0
$("<span rel='tooltip' title='Started Ranking' class='yesterday'> <b>new</b> </span>").addClass("sortboxnew").css(css).appendTo(changes)
else if a < b && a is 0 && b > 0
$("<span class='yesterday' rel='tooltip' title='Dropped'> <b>Dropped</b> </span>").addClass("sortboxdrop").css(css).appendTo(changes)
else if a < b
$("<span rel='tooltip' title='Increased' class='yesterday'> <b>#{b - a}</b> </span>").addClass(sortboxarrowup).css(css).appendTo(changes)
else if a is b | {
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c#, design-patterns, entity-framework, dependency-injection, ninject
public virtual TEntity GetByID(object id)
{
return _dbSet.Find(id);
}
public virtual void Insert(TEntity entity)
{
_dbSet.Add(entity);
}
public virtual void Delete(object id)
{
TEntity entityToDelete = _dbSet.Find(id);
Delete(entityToDelete);
}
public virtual void Delete(TEntity entityToDelete)
{
if (_context.Entry(entityToDelete).State == EntityState.Detached)
{
_dbSet.Attach(entityToDelete);
}
_dbSet.Remove(entityToDelete);
}
public virtual void Update(TEntity entityToUpdate)
{
_dbSet.Attach(entityToUpdate);
_context.Entry(entityToUpdate).State = EntityState.Modified;
}
}
ICityRepository
public interface ICityRepository : IGenericRepository<City>
{
}
CityRepository
public class CityRepository : GenericRepository<City>, ICityRepository
{
public CityRepository(IMainContext context) : base(context)
{
}
} | {
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beginner, c, io
Then, the display() function could be written like this:
void display(char *string, int (*transform)(int))
{
for (char *s = string; *s; s++)
{
*s = transform(*s);
}
puts(string);
} | {
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organic-chemistry, stability, carbohydrates
I understand in nature, these are the most stable rings. However, what thermodynamic incentive does the furanose form have? That is, why would $\mathrm{C4}$'s alcohol attack and form a 5-membered ring at the expense of the $\ce{CH2OH}$ group and the $\ce{OH}$ group being near each other as a side chain on the 5-membered ring? Doesn't this introduce considerable strain? My idea is that the 6-memebered ring is more thermodynamically stable and it doesn't have the problem of a hydroxymethyl and a hydroxyl group on a single carbon of the 5-membered ring. If you look up the statistical distribution of glucose isomers in aquaeous solution, you will find $36\,\%$ $\unicode[Times]{x3B1}$-pyranose and $64\,\%$ $\unicode[Times]{x3B2}$-pyranose. All the remaining forms lumped together only account for less than $1\,\%$ of glucose in solution; that includes both furanoses, the open-chain form and the (possible, but unlikely) seven- and four-membered rings. | {
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ros2, jenkins
ros_humble_default.html: the "default" OS for Humble, being Ubuntu Jammy
ros_humble_rhel.html: Humble on RedHat Enteprise Linux
ros_humble_ujv8.html: Humble on Ubuntu Jammy on ARMv8 (or arm64, as opposed to something like armhf)
If you open the first one, and filter for rclcpp, you get this page:
The links to the buildfarm jobs are "hidden" in the last two columns: Jsource and J64. That would be the source jobs and the amd64 binary jobs respectively. The squares can have different colours than green, and the page has a legend for what those other colours would mean which I won't duplicate here.
The first square in each column links you to a job. For rclcpp that would be:
Hsrc_uJ__rclcpp__ubuntu_jammy__source: the source job for rclcpp in Humble, on Ubuntu Jammy
Hbin_uJ64__rclcpp__ubuntu_jammy_amd64__binary: the binary job building rclcpp in Humble, for Ubuntu Jammy on amd64 | {
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Asked in the form of e+ if where e and f are real is! Before solving the Class 11 Maths with Answers were prepared based on the latest exam pattern visioned upon your dreams! Customised services that resonate with your personal career needs questions on complex Numbers a. Of Unity Back to Maths home Page Physics Chemistry Biology any question and improve application skills while preparing the! Try to solve mcq based on the latest exam pattern tips, and offers at Leverage experts. Based on NCERT Text book for Class XI cover this topic from basic also will. Data-First approach at Leverage Edu Vedic Maths Maths for Competitive exams your friends Support US to Provide free Subscribe! Along with NCERT Exemplar questions not only helps for exam preparation but for! Your friends Support US to Provide free Education Subscribe to US on YouTube Next > Try Further learning steps CISCE. On this definition, complex Numbers will advance your knowledge by introducing the concept of complex numbers- | {
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entomology
Title: How to protect my mounted insect specimens from ... insects? I have a modest collection of insect specimens that I caught, prepared, mounted, and dried myself. I'm entirely an amateur collector, so my procedure may be causing me this trouble now, but here's how I preserved them.
Killed in the freezer
Placed in a sealed container on a dry platform, with a 50% isopropyl alcohol solution under it. This lets the specimen thaw and remain moist, while the alcohol prevents rotting.
Kept in container for two to three days.
Stretched over foam and held in place with paper and pins.
Kept on stretching board for three weeks.
Placed in a consumer grade display box.
Stored in a dark, dry closet. | {
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combinatorics
Now say that the fixed point is $(0,0)$. You are interested in the number of points $(x,y)$ such that
$$ |x| + |y| \leq k. $$
This is something you can solve on your own. | {
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java, thread-safety, primes
int pos = estate.primes.length;
int[] primes = Arrays.copyOf(estate.primes, pos + cnt);
for (int i = 0; i < sieve.length; i++) {
if (!sieve[i]) {
primes[pos++] = offset + i;
}
}
return new PrimeState(primes);
}
}
PrimeTester.java
(used to test the generator)
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
public class PrimeTester { | {
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ros
Original comments
Comment by Pi Robot on 2012-09-10:
Thanks @Lorenz. Is mux (http://ros.org/wiki/topic_tools/mux) what you had in mind for mutiplexing? I just stumbled upon it now after reading your answer.
Comment by Lorenz on 2012-09-10:
That multiplexer might not be exactly what you need because it relays from multiple input topics to one output topic. Instead, I would implement a mux that has one input topic and multiple output topics.
Comment by dornhege on 2012-09-11:
The multiple input version could be useful for the "manually override" of the headtracker, similar like a joystick control would interfere with move_base.
Comment by Pi Robot on 2012-09-11:
Yes, last night I tried mux for the "manual override" situation and it works nicely for that. For switching between the face tracker and color tracker, I need a different method since part of the goal would be to save CPU cycles by not having the unused tracker processing frames while "idle". | {
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## Displacement – A Numerical Problem
A fly is sitting in the middle of a wall of a cubic room of side ’a’.If it flies and sit to one of opposite corner of the wall. Find its displacement?
If the fly sit on the same wall on the horizontal, (from A to B in the diagram) the displacement is “a
If the fly sits on the diagonally opposite corner on the same wall, (from A to C in the diagram) the displacement is “√2 a
If the fly sits on the corner on the longest diagonal of the room, (from A to H in the diagram) the displacement is “√3 a
## Problem from Vectors and Kinematics
“Over the course of about six weeks in 1992, Aki Matusushima, from Japan, rode a unicycle more than 3000 mi across the United States. Suppose Matsushima is riding through a city. If he travels 250.0 m east oone street, then turns counterclockwise through a 120 degree angle and proceed 125.0 m northwest along a diagonal street, what is his net displacement?” | {
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general-relativity, metric-tensor, stress-energy-momentum-tensor, wick-rotation
That being said, apparently the idea of spacetimes which contain multiple regions of different metric signature has been kicked around for a while. A quick search of the arXiv yields this paper, and the subsequent 23 papers which have cited it which you might find interesting. I am nowhere close to an expert on even standard GR, much less fairly dramatic extensions of it, so this is where my ability to speak coherently on the topic ends. | {
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evolution
If you treat a population of bacteria with an antibiotic, some may die and some may live.
If none die, they are obviously resistant.
If all of them die, then all of them were sensitive, meaning that the size of the population and the variation were not large enough in order for some of the bacteria to be resistant. One approach would be to try to get larger genetic variation by inducing mutations with some mutagen. In addition, you can take a larger population. This would in effect let you sample a larger part of the genetic space to see if you can find a resistant strain. Of course it is possible that this will not work. | {
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Because each table is arranged independently from the arrangements of the previous tables, you can apply the product principle. So, the total is:
$$(6\cdot 6\cdot 2)(5\cdot 5\cdot 2)(4\cdot 4\cdot 2)(3\cdot 3\cdot 2)(2\cdot 2\cdot 2)(1\cdot 1\cdot 2) = 2^6(6!)^2$$
• Perfect, thank you! Dec 16, 2019 at 16:47
In the first reference, the boys and girls are sitting in a line with no two people of the same gender are allowed to sit together. So there can be two cases. First in which a boy sits first and the second when a girl sits first. While in your case as you've mentioned in the comments there can be two possibilities for each table GB or BG. Thus you have a multiplier of 2 for each table along with every permutation of boys and girls.
In other words, $$2*(6!)^2$$ is equivalent to the case when each table should have the same layout i.e either all the table should be BG or GB, while $$2^6*(6!)^2$$ is the case where each table can BG or GB independent of the other. | {
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statistics
fault density was not as effective as sorting files according to fault
count at finding large numbers of faults, but it does result in considerably less code in the end.
Fenton and Ohlsson [84] investigated, among many hypotheses,
the Pareto principle [28] and the relationship between size metrics
and the number of faults. They used a graphical technique called
the Alberg diagram [127] and two versions of a telecommunication
software. As independent variables LOC, McCabe’s cyclomatic complexity and SigFF metrics were used. In pre-release 20% of the modules were responsible for nearly 60% of the faults and contained
just 30% of the code. A replicated study by Andersson and Runeson
[59] found an even larger proportion of faults, in a smaller proportion of the modules. This result is also in agreement with
[130,151]
Fenton and Ohlsson also tested the hypothesis of whether size
metrics (such as LOC) are good predictors of pre-release and | {
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ros, gazebo, gazebo-4
they are running fine. My doubt was how to spawn the hector quad into a custom world I created using gazebo4 and use it there?
Comment by evilBiber on 2015-09-08:
The hector_quadrotor_gazebo package has a set of launch files which you can use. If you need to specify a position you can with the provided command line args... | {
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