text stringlengths 49 10.4k | source dict |
|---|---|
waves, computational-physics, simulations, differential-equations
Title: How to simulate 1D waves starting from the acceleration (second derivative)? Knowing that a 1D wave with the physical form parametrized by x and t
$$u = \sin(x-t)$$
will yield us the first time derivative $$\frac{\partial u}{\partial t} =-\cos(x-... | {
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"openwebmath_score": null,
"tags": "waves, computational-physics, simulations, differential-equations",
"url": null
... |
homework-and-exercises, electric-circuits, electric-current, electrical-resistance
Title: How to determine direction of the current in the following circuit?
What would be the direction of the current on R3? Can there be current moving in both directions?(left and right?)
So how do I write Kirchhoff's Voltage Law if... | {
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quantum-field-theory, regularization
$$
L = (N+1)\,d, \qquad \lambda = \frac{(N+1)\,m}{L}, \qquad v = \sqrt{T/\lambda}.
$$
Writing the normal mode frequencies in terms of these parameters gives
$$
\omega_n = \frac{2v}{d}\sin\left(\frac{n\pi d}{2L}\right).
$$
The limit in which the loaded string becomes a continuou... | {
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"tags": "quantum-field-theory, regularization",
"url": null
} |
organic-chemistry, stability, carbocation
Title: What exactly is "B-strain"? On factors that influence the stability of carbocations, I came across this peculiar one:
Bulky groups attached to the positively charged $C$-atom (of the carbocation), stabilize it by B-strain, which prevents the C-atom for returning to the... | {
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"tags": "organic-chemistry, stability, carbocation",
"url": null
} |
c++, performance, c++11, breadth-first-search, chess
While common in C, this is not needed in C++ since the name of the struct type is already available as a type. That line should simply be:
struct KMBaseData {
// ...
};
Then replace each instance of KnightMovesBaseData with KMBaseData. It's usually better to ... | {
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We can prove this by structural induction over the factors. So let some multiple product of polynomials be given, and focus on the "outermost" multiplication, the one to be applied last. We have
$$p(x) = \sum_{i=0}^n a_i x^i, \ \ q(x) = \sum_{i=0}^m b_i x^i\;,$$
where $p(x)$ and $q(x)$ are the results of carrying out... | {
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rviz, ros-kinetic
Originally posted by dljubic with karma: 516 on 2018-04-07
This answer was ACCEPTED on the original site
Post score: 1
Original comments
Comment by stefanvan on 2018-04-07:
@dljubic I just tried using rostopic echo /scan, then a lot of 0.0 were shown on the terminal.
Here is the output of rostopic ... | {
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java, beginner
It would be helpful to keep consistent in the way you format your code. It makes it easier for a reader to parse. Also, you have some weird indentation going on in your last function.
isarmstrong() function
First of all, the function as written is way too complicated for what it does. It could be rew... | {
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python, algorithm, object-oriented, python-3.x, mobile
class output:
""" Output helpers """
def header(text):
print("\n--- " + text + " ---\n")
def clear():
print("\n" * 50)
if __name__ == "__main__":
Console.output.clear()
while True:
# print header
print("Bratwurst p... | {
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general-relativity, mathematical-physics, black-holes, topology
\begin{equation}
\mathrm{const}\ \int_{\partial \mathscr{B}} \mathrm{vol}^n = \int_{\partial \mathscr{B}} \left( - R_{ac} Y^{a}_{1} Y^{c}_{2} + R_{adcb} Y^{d}_{1} Y^{c}_{2} Y^{a}_{2} Y^{b}_{1} \right)\ \mathrm{vol}^n.
\end{equation}
The integral on the ... | {
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Where $\Delta x=\frac{a}{n}$. For the other area,
$$A_{1}=\lim_{n \to \infty }\sum_{i=1}^{n}f(-x_{i})\Delta x =\lim_{n \to \infty }\sum_{i=1}^{n}f(-x_{i})\frac{a}{n}$$$$=\frac{a}{n}\lim_{n \to \infty }\sum_{i=1}^{n}f(-x_{i})=\frac{a}{n}\lim_{n \to \infty }\sum_{i=1}^{n}-f(x_{i})=\frac{-a}{n}\lim_{n \to \infty }\sum_{i... | {
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"tags... |
c, generics, quick-sort
That saves one iteration of the outer loop without changing behavior. This is because the inner loop won't run when i and j are 0.
Don't subtract and multiply when you can just do one
char *carray = (char *)base;
unsigned int i;
int j;
for(i = 0; i < nitems; i++)
{
... | {
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compilers, parsing, ambiguity
is concatenation.
Fortress's syntax has (or had) a number of other issues which are harder to solve with a simple yacc/lex parser; if I recall correctly, the proof-of-concept implementation used a packrat parser. For example, the syntax allows the use of vertical bars either as operators ... | {
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"tags": "compilers, parsing, ambiguity",
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# Math Help - Help with finding quadratic equation.
1. ## Help with finding quadratic equation.
hello, totally new here
and i'm having trouble deriving the equation out of this question...
so here's the question:
Alex was practising his 10m platform dive (i'm assuming that it means, he's above the water by 10m?). Bec... | {
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"ta... |
## Implementation¶
It is typical to use just the minimal formula $$S_f(4)$$ and its error estimate $$E$$ to make decisions about adaptivity. A computation of $$S_f(4)$$ requires three trapezoid estimates $$T_f(1)$$, $$T_f(2)$$, and $$T_f(4)$$. As observed in (5.6.13) and Demo 5.6.8, the five integrand evaluations in $... | {
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"lm_q2_score": 0.8438951005915208,
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"openwebmath_score": 0.818678617477417,
"tags... |
python, python-3.x
raise RuntimeError('could not place the requested boats')
def place_selected_boat(self, size, patience):
for _ in range(patience):
# try to place boat of current size
point = random.choice(tuple(self.__available))
method = random.choice(tuple(Orientation))
try:
... | {
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scheme, makefile, make
Title: Standalone GNU Makefile tracking `@import` statements in Sass The following is a (working) excerpt from the Makefile I want to use in web projects. I wanted this Makefile to contain all the necessary code and not rely on other self-written files. Partly, because I'm stubborn, partly becau... | {
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"tags": "scheme, makefile, make",
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c#, unit-testing, validation, extension-methods, framework
and a real-world usage example:
public static bool IsStatic(this Type type)
{
type.Validate(nameof(type)).IsNotNull();
return type.IsAbstract && type.IsSealed;
} | {
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ds.algorithms, graph-algorithms, shortest-path
I don't need to enumerate the paths.
I'm looking for an efficient algorithm (both time and memory), as I need to execute it over very large graphs (10^8 vertexes, 10^9 edges). Well, the problem is in $P$ after all.
I'll keep the previous answer as it also works for the di... | {
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"tags": "ds.algorithms, graph-algorithms, shortest-path",
"url": null
} |
image-processing, filters, downsampling
Title: Downsampling and low pass filtering in one step? Image pyramids are created by applying a lowpass filter (Gaussian) and then decimating the image (keeping only every n'th sample).
In The Pyramid as a Structure for Efficient Computation the start image is 257x257. Then the... | {
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So rings like these are actually "close" to integral domains, which are quotients of arbitrary commutative rings by prime ideals. Again, no quantitative argument for why they should be rare, only an intuitive one.
• Couldn't one equip a ring $R$ with the Zariski topology, then produce a Borel sigma algebra, and equip ... | {
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"lm_q2_score": 0.875787001374006,
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"openwebmath_score": 0.8839941620826721,
"tag... |
algorithm-analysis, asymptotics, recurrence-relation, master-theorem
Thus case 1 of the Master theorem should apply, and $T(n) = \Theta(n^{2/3})$. | {
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"tags": "algorithm-analysis, asymptotics, recurrence-relation, master-theorem",
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} |
quantum-information, wavefunction, quantum-computer, superposition
And thus the entire system now is in:
$$ \frac{q_0 + q_1+q_2 + q_3}{\sqrt{2}} \frac{q_0}{q_0 + q_1}\left| 00 \right> +\frac{q_0 + q_1+q_2 + q_3}{\sqrt{2}} \frac{q_1}{q_0 + q_1} \left| 01 \right> + \frac{q_0 + q_1-q_2 - q_3}{\sqrt{2}} \frac{q_2}{q_2 ... | {
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"tags": "quantum-information, wavefunction, quantum-computer, superposition",
"url": null... |
asp.net, vb.net, authentication
The article contains more information and links to other resources.
Solution
Make the tr server-side by adding runat="server" to to the tag and give it an ID. Now you can access the tr-tag from the code-behind and set it's visibility property. Example:
Markup
<tr id="myRow" runat="serv... | {
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# How many $4$-letter strings either start with c or end with two vowels?
If the alphabet consists of $\{a,b,c,d,e,f\}$, how many four letter strings either start with c or end with two vowels?
My reasoning was as follows:
Starts with c but does not have vowel in third position + starts with c but does not have a vo... | {
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"openwebmath_score": 0.7891740202903748,
"ta... |
perl, linux, email
Explanation of other improvements:
Removed unnecessary brackets from the if condition
Simplified $_ =~ m// to just m// which does the same
Instead of chomp($svr) for each line, do it only once, right after initialization
Reindented, so it's easier to see the block of code that belongs to the loop
... | {
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"tags": "perl, linux, email",
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beginner, c, strings, programming-challenge
bool is_rotated(char *original, char *test_case) {
int original_length = strlen(original);
char rotation_superset[LINE_LENGTH*2];
str_mul(original, rotation_superset, 2);
bool is_substring = strstr(rotation_superset, test_case) != NULL;
return original_le... | {
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"tags": "beginner, c, strings, programming-challenge",
"url": null
} |
java, strings, converting, integer
Be careful with inlined ++i or i++. They can be easy to overlook, and the human brain (mine anyway) doesn't parse arithmetic expressions that cause mutations very well.
I think you've overused parenthesis a bit. For example, I would just do:
if (c >= 'A' && c <= 'Z') {
playerNameToI... | {
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"openwebmath_score": null,
"tags": "java, strings, converting, integer",
"url": null
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c++, role-playing-game
qUpdates = "Quest updated";
qStages = "Kill the thief in Rat Cave";
questUpdate();
riverstead();
case 2:
system("cls");
cout << "\n That's a shame. Talk to me if you change your mind." << endl;
cout << "\n ";
system("pause");
... | {
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"openwebmath_score": null,
"tags": "c++, role-playing-game",
"url": null
} |
electromagnetism, electromagnetic-radiation, electric-fields, charge, microwaves
Title: Charge Distribution on a Strip let's consider a microstrip line connected to a voltage source V0 (applied between the strip and GND plane). According to foundation for microwave engineering (collin) book, the surface charge density... | {
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"tags": "electromagnetism, electromagnetic-radiation, electric-fields, charge, microwaves",... |
ruby, http, email, web-scraping
You might consider changing if continue.chomp.to_bool == false to unless continue.chomp.to_bool, or even if continue.chomp == "false". In fact, I think I like the last way the best -- you could totally do away with monkey-patching a String#to_bool method and just compare continue.chomp ... | {
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"openwebmath_score": null,
"tags": "ruby, http, email, web-scraping",
"url": null
} |
interview-questions, go, chat
var address = flag.String("address", ":8081", "the address for the chat HTTP server to listen on")
func main() {
state := chat.NewInMemoryState()
server := chat.NewHTTPServer(state)
log.Println(server.ListenAndServe(*address))
}
Note that the signature of NewHTTPServer is:
f... | {
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"tags": "interview-questions, go, chat",
"url": null
} |
c++, algorithm, interview-questions, c++17, computational-geometry
class Polygon {
public:
Polygon(const vector<Point>& points) : points_{points} {};
Polygon(const vector<Point>&& points) : points_{move(points)} {};
// Returns true if point is in Polygon, false otherwise.
// Unimplemented.
bool contains(c... | {
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"tags": "c++, algorithm, interview-questions, c++17, computational-geometry",
"url": n... |
hamiltonian-simulation, terminology-and-notation
You can repeat this squaring process to get $P$, $P^2$, $P^4$, $P^8$, $P^{16}$, and so forth up to $P^{2^m}$ for any reasonable sized $m$ you'd like. If you want to simulate for $t$ steps, set $m = \lceil \lg t \rceil$. You can then compute $P^t$ by multiplying together... | {
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"tags": "hamiltonian-simulation, terminology-and-notation",
"url": null
} |
algorithms, data-structures, arrays, hashing
It is working fine on some test cases I tried. But I have a doubt: in the hashtable we are just storing one occurrence of each pair, but there can be a case in which a solution exists, but since we stored only one occurrence of each pair, we only have overlapping occurrence... | {
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"url": null
} |
first day of the rest of your life. Complex Conjugate Poles Obtaining the PFE - Recipe Examples PFE in Matlab 9 / 12 To every simple pair of complex conjugate poles at s =α ±βi there correspond two terms of the form A(s−α) (s−α)2+β2 + B (s−α)2+β2 The quantities a, c i, A and B are called residues. Chapter 8 HW Solution... | {
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"openwebmath_perplexity": 759.7709307969543,
"openwebmath_score": 0.6477792859077454,
"tags": nu... |
sql, sql-server, t-sql
10101,08-Mar-10,Sleeping Bag,2,88.7
10298,18-Mar-10,Pocket Knife,1,22.38
10449,19-Mar-10,Canoe paddle,2,40
10298,01-Apr-10,Ear Muffs,1,12.5
10330,19-Apr-10,Shovel,1,16.75 Data location
This is probably a weirdness from MSSQL itself and not specifically your setup, but your database location:
FIL... | {
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"tags": "sql, sql-server, t-sql",
"url": null
} |
c#, beginner, object-oriented
return 0;
}
private static String HandleInput(String input)
{
String output;
Console.WriteLine(input);
output = Console.ReadLine();
Console.WriteLine("");
return output;
}
private st... | {
"domain": "codereview.stackexchange",
"id": 24306,
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"openwebmath_score": null,
"tags": "c#, beginner, object-oriented",
"url": null
} |
c#, beginner, database, ado.net
DbCommandBuilder commandBuilder = dbProvider.CreateCommandBuilder();
//uses reflection to get method
MethodInfo method = commandBuilder.GetType().GetMethod("DeriveParameters", BindingFlags.Public | BindingFlags.Static);
method.Invoke(null, new object[] { command ... | {
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"openwebmath_score": null,
"tags": "c#, beginner, database, ado.net",
"url": null
} |
graphs, trees, shortest-path
Title: Algorithm to find the shortest walk with k leaf nodes on a tree Let's say I have a general tree. What algorithm can I use to find a shortest walk that starts at the root, passes through exactly $k$ different leaves, and ends at the root? Passing through a node/edge more than once i... | {
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"lm_q2_score": null,
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"openwebmath_score": null,
"tags": "graphs, trees, shortest-path",
"url": null
} |
formal-grammars
Title: What does the term "top-most" mean in the context of formal grammars? I was learning about disambiguating grammars. In particular I was learning about enforcing right associativity on the sum language here:
$$ \mathit{Sum} ::= 0 \mid 1 \mid \mathit{Sum} + \mathit{Sum} \mid ( \mathit{Sum} )$$
I t... | {
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"id": 15036,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "formal-grammars",
"url": null
} |
php, mysql, php5, pdo
Title: Database class using PDO The point of this question
I'm actually using it while developing a simple application and it seems to cover all my needs. Also it uses PDO so that we don't really have to worry about SQL Injection. I know I usually code strange, but I hope you could give me sugges... | {
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"id": 84,
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"lm_q1_score": null,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "php, mysql, php5, pdo",
"url": null
} |
reinforcement-learning, q-learning, actor-critic-methods
Title: Relationship between Rewards and Q Value (Graph between Q(s, a) vs episodes) I'm employing the Actor-Critic algorithm. The critic network approximates the action-value function, i.e. $Q(s, a)$, which determines how good a particular state is, when provide... | {
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"id": 2581,
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"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "reinforcement-learning, q-learning, actor-critic-methods",
"url": null
} |
electromagnetism, field-theory, lagrangian-formalism
\:\vphantom{\dfrac{\dfrac{a}{b}}{\dfrac{a}{b}}}}
\tag{011}
\end{equation}
Here the Lagrangian density $\:\mathcal{L}\:$ is a function of | {
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"openwebmath_score": null,
"tags": "electromagnetism, field-theory, lagrangian-formalism",
"url": null
} |
botany, species-identification, mycology
Title: What are those huge plants / fungi on trees called? I've seen them in Scotland in August 2015:
The plants / fungi were quite high (over 2m) on the tree. They are almost circular if you view them from the top, I guess (except for the part where they are connected to the ... | {
"domain": "biology.stackexchange",
"id": 4471,
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"lm_q1q2_score": null,
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"openwebmath_score": null,
"tags": "botany, species-identification, mycology",
"url": null
} |
Menu Close
# Can a sequence be non decreasing and non increasing?
## Can a sequence be non decreasing and non increasing?
A sequence which is either increasing, decreasing, non-increasing, or non-decreasing is called a monotone sequence.
## Is non decreasing increasing?
2 Answers. Nondecreasing means that the valu... | {
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"id": null,
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"lm_q2_score": 0.8221891283434876,
"openwebmath_perplexity": 580.5350384796975,
"openwebmath_score": 0.8924967646598816,
"tags... |
c#, api, asp.net-mvc, wrapper, fluent-interface
public static SalesApiOptions SetPickDateRange(this SalesApiOptions options, DateTime start, DateTime end) {
options["startPickDate"] = start.ToPPROFormattedDate();
options["endPickDate"] = end.ToPPROFormattedDate();
return options;
}
pub... | {
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"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "c#, api, asp.net-mvc, wrapper, fluent-interface",
"url": null
} |
python, beginner, python-2.x, hangman
global word
word = words[key]
global word_template
word_template = '_' * len(word)
word_template = list(word_template)
guesser()
def draw(int):
if int == 0:
print " _________ "
print "| | "
print "| ... | {
"domain": "codereview.stackexchange",
"id": 19853,
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"openwebmath_score": null,
"tags": "python, beginner, python-2.x, hangman",
"url": null
} |
The derivatives of the inverse trigonometric functions can be obtained using the inverse function theorem. Here is a set of practice problems to accompany the Derivatives of Inverse Trig Functions section of the Derivatives chapter of the notes for Paul Dawkins Calculus I course at Lamar University. In each pair, the d... | {
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"id": null,
"lm_label": "1. YES\n2. YES\n\n",
"lm_name": "Qwen/Qwen-72B",
"lm_q1_score": 0.9648551546097941,
"lm_q1q2_score": 0.8081819392261907,
"lm_q2_score": 0.8376199633332891,
"openwebmath_perplexity": 1399.5504038876154,
"openwebmath_score": 0.7149947285652161,
... |
java, linked-list
// return node at particular index
private DoublyLinkedListNode<T> nodeAtIndex(int index){
if(index<0){
return null;
}else{
DoublyLinkedListNode<T> nodes=head.getNextNode();
int i=0;
while(i < index && nodes != null){
... | {
"domain": "codereview.stackexchange",
"id": 24091,
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"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "java, linked-list",
"url": null
} |
gpt, azure-ml
Title: Where can I find gpt-35-turbo in the Microsoft Pricing calculator? Where can I find gpt-35-turbo in the Microsoft Pricing calculator? I don't see gpt-35-turbo in the model list:
https://azure.microsoft.com/en-us/pricing/details/cognitive-services/openai-service/ says "NA".
However, I do see gpt-3... | {
"domain": "datascience.stackexchange",
"id": 11943,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "gpt, azure-ml",
"url": null
} |
c#, recursion
Title: Base 256 array addition Recursively - Follow up This is a follow up code review request from Base 256 array addition Recursively
I have made the changes that were suggested for the RecursiveAdd method. Please take some time to review and help me to make it better.
public class Base256Calculator : ... | {
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"openwebmath_score": null,
"tags": "c#, recursion",
"url": null
} |
python, python-3.x, playing-cards
def _display_winning_cards(self, winner, winning_cards):
while winner[-1] == ' ':
winner = winner[:-1]
if winner[-1].lower() == 's':
winner += '\''
else:
winner += '\'s'
print('\n%s CARDS:\n' % winner.upper())
... | {
"domain": "codereview.stackexchange",
"id": 32314,
"lm_label": null,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "python, python-3.x, playing-cards",
"url": null
} |
ros-kinetic
Title: Multiple image subscriber failure
I made 2 nodes, publishing my web camera and external camera images.and I want to show both camera images with a single subscriber node. but when i run my subscriber node, it publishes camera 1 and 2 images alternatively.( if i run subscriber code for the first tim... | {
"domain": "robotics.stackexchange",
"id": 30595,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "ros-kinetic",
"url": null
} |
approximation-algorithms, approximation-hardness
Title: Is the current best approximation ratio for Vertex Cover problem also a lower bound? In textbook "Introduction to Algorithms" by Cormen, Leiserson, Rivest and Stein. in pp.1110-1111, they argue that the vertex-cover problem is a 2-approximation algorithm and it i... | {
"domain": "cstheory.stackexchange",
"id": 4604,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "approximation-algorithms, approximation-hardness",
"url": null
} |
When we add $10$ red, we end up with $4k+10$ red. The blues remain unchanged at $7k$.
So the new proportion is $(4k+10): 7k$. We are told that the proportion $(4k+10): 7k$ is $6:7$. So $$\frac{4k+10}{7k}=\dfrac{6}{7}.$$ If we multiply through by $7k$, we get $4k+10=6k$, and therefore $k=5$. It follows that there are $... | {
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"id": null,
"lm_label": "1. YES\n2. YES",
"lm_name": "Qwen/Qwen-72B",
"lm_q1_score": 0.9796676466573413,
"lm_q1q2_score": 0.8120845274311583,
"lm_q2_score": 0.8289388040954684,
"openwebmath_perplexity": 397.0230083135,
"openwebmath_score": 0.9227442145347595,
"tags":... |
c++, object-oriented, socket, callback, tcp
// setup winsock event handling
int ret = WSAEventSelect(pimpl_->socket_, pimpl_->comms_event, FD_READ | FD_CONNECT | FD_CLOSE);
if (ret != 0) {
int lasterror = WSAGetLastError();
std::string s = "Winsock communication error - unable to create event ... | {
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"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "c++, object-oriented, socket, callback, tcp",
"url": null
} |
c, windows, networking, child-process
void printResultsPingMean(char* path, char* ip) {
FILE* fp = fopen(path, "r");
printf("Results from %s\n", ip);
char buffer[MAX_LEN];
char* line;
if (fp == NULL) {
printf("File not foudn\n");
}
else {
while (fgets(buffer, MAX_LEN, fp)) {... | {
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"openwebmath_score": null,
"tags": "c, windows, networking, child-process",
"url": null
} |
classification, feature-selection, correlation
Title: Correlations, p-values and features selection By using correlation matrix, I got some results:
Count_words -0.098857
Count_numbers -0.008305
Count_symbols -0.025853
Count_question -0.031649
Count_equal 0.224223
Count_character... | {
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"openwebmath_score": null,
"tags": "classification, feature-selection, correlation",
"url": null
} |
navigation, ros-kinetic, amcl
Well, if the battery gets low and the motors shut down, it could very well be that the odometry is still being published. If communication is down, some drivers still publish the last value.
My guess is that this is the problem
As mgruhler said to opencr stops sending cmd_vels to the mot... | {
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"tags": "navigation, ros-kinetic, amcl",
"url": null
} |
r
Title: Achieve a dataframe from a dynamic list of lists This code works for me, but I am trying to improve my coding and am looking for advice on how to improve it. Specifically I want to simplify this so that perhaps I can have a dynamically updating dataframe that tracks the "site" that I am on, and the "cutoff" v... | {
"domain": "codereview.stackexchange",
"id": 18740,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "r",
"url": null
} |
quantum-mechanics, statistical-mechanics
To reconcile it with the QM result, you can directly quantize from the Euler angles, ie enforce canonical commutation relations for the three degrees of freedom. This is not equivalent to your original system. Indeed, you underestimate the degeneracy of the $L^2$ eigenspace as ... | {
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"openwebmath_score": null,
"tags": "quantum-mechanics, statistical-mechanics",
"url": null
} |
visible-light, waves, vacuum
Also, please explain why either happens if I missed something. Heisenberg's uncertainty principle?
See Wikipedia and note this sentence: "It has since become clear, however, that the uncertainty principle is inherent in the properties of all wave-like systems". It's to do with waves, not ... | {
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"id": 25201,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "visible-light, waves, vacuum",
"url": null
} |
java, multithreading, android, timer
Title: Android splash screen I have implemented a splash screen, to hold/pause the screen for few seconds and then launch the next screen. I am very enthusiastic to know if there is a more basic way to write the code.
public class SplashActivity extends BaseActivity {
private ... | {
"domain": "codereview.stackexchange",
"id": 19983,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "java, multithreading, android, timer",
"url": null
} |
java, optimization, beginner, android
try
{
output = new ObjectOutputStream( new FileOutputStream(new File(getActivity().getApplicationContext().getFilesDir(),"")+File.separator+USER_INFO_FILE));
output.writeObject(savedUserInfo);
output.close();
}
catch (FileNotFoundException e)
{
e.printStackTrace();
}
catch (IOExce... | {
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"id": 12085,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "java, optimization, beginner, android",
"url": null
} |
acceleration, velocity, speed
if you get accleration as a raw number and angle then you will have to convert from I guess polar coordinates to xyz components to be able to add them up.
Total speed, $|v|$ is, of course, given by $|v|=\sqrt{v_x^2 + v_y^2 + v_z^2}$
I would, of course, try to start at $v=0$
Curious One, ... | {
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"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "acceleration, velocity, speed",
"url": null
} |
Arrange $2$ red books. Arrange the $5$ black books in any of the three positions as [bbb] [bb]. Take $3$ blue books and separate the adjacent bbb and bb. Remaining $3$ books can be arranged in remaining $5$ positions. So,
$\dbinom{3}{1}\dbinom{2}{1}\dbinom{5}{3}=60$
Arrange $2$ red books. Arrange the $5$ black books i... | {
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"lm_label": "1. YES\n2. YES",
"lm_name": "Qwen/Qwen-72B",
"lm_q1_score": 0.9830850872288502,
"lm_q1q2_score": 0.8296206924366494,
"lm_q2_score": 0.8438951045175643,
"openwebmath_perplexity": 371.0088924405376,
"openwebmath_score": 0.6926159858703613,
"tag... |
Theorem. [Sperner’s Theorem]
$|S| \leq {n \choose \lfloor n/2 \rfloor}.$
The proof of Sperner’s Theorem follows from the following lemma, which is known as LYM (Lubell–Yamamoto–Meshalkin) inequality.
Lemma. [LYM Inequality]
$\sum_{A\in S} \frac{1}{n \choose |A|} \leq 1.$
Proof. The proof follows from a double counti... | {
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"id": null,
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"lm_name": "Qwen/Qwen-72B",
"lm_q1_score": 0.9833429629196684,
"lm_q1q2_score": 0.8172986590652488,
"lm_q2_score": 0.8311430394931456,
"openwebmath_perplexity": 821.3708107827065,
"openwebmath_score": 0.876673698425293,
"tags": n... |
python, python-3.x, tree
delete
The delete operation needs the two following steps: 1. find the node having the given key; 2. remove the key. The first step is easy, now but the second one is not. Let's look at your code to understand what happens:
else: # key == cur.key
if cur.left is None:
re... | {
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "python, python-3.x, tree",
"url": null
} |
geometry, aircraft, rotation
Title: Does the rotation of the earth dramatically affect airplane flight time? Say I'm flying from Sydney, to Los Angeles (S2LA), back to Sydney (LA2S).
During S2LA, travelling with the rotation of the earth, would the flight time be longer than LA2S on account of Los Angeles turning/movi... | {
"domain": "physics.stackexchange",
"id": 1820,
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"lm_name": null,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "geometry, aircraft, rotation",
"url": null
} |
## EBook - Multivariate Normal Distribution
The multivariate normal distribution, or multivariate Gaussian distribution, is a generalization of the univariate (one-dimensional) normal distribution to higher dimensions. A random vector is said to be multivariate normally distributed if every linear combination of its c... | {
"domain": "ucla.edu",
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"lm_q1_score": 0.9857180660748889,
"lm_q1q2_score": 0.8035893928054708,
"lm_q2_score": 0.815232489352,
"openwebmath_perplexity": 644.6473505815802,
"openwebmath_score": 0.9054813385009766,
"tags": null,
"... |
electromagnetism, magnetic-fields, electric-current, induction
SOLUTION: the flux through the loop is
$$
\Phi(\vec{B_{I_0}}) = \int_S\vec{B_{I_0}}\cdot\hat{n}\ \mathrm{d}S = \int_d^{d+l}\frac{l\mu_0I_0}{2\pi r}\ \mathrm{d}r = \frac{l\mu_0I_0}{2\pi}\ln{\frac{d+l}{d}}
$$
Now for the Faraday's law I can calculate the $e... | {
"domain": "physics.stackexchange",
"id": 41028,
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"openwebmath_score": null,
"tags": "electromagnetism, magnetic-fields, electric-current, induction",
"url": null
} |
molecular-genetics, cancer, rna
Title: Why is mRNA used as a biomarker for cancer over tRNA or rRNA? I cannot find a clear explanation for why mRNA is used as cancer biomarker and not tRNA or rRNA. Is there something peculiar about mRNA which cannot be fulfilled by tRNA or rRNA? mRNAs encode specific genes and perfor... | {
"domain": "biology.stackexchange",
"id": 5176,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "molecular-genetics, cancer, rna",
"url": null
} |
quantum-mechanics, homework-and-exercises, operators, commutator
Title: How does the following commutator for measured observables and this operator relation imply the following relation? $$
\hat{\Omega}_j{(\tilde{q}_j)}=\Omega_j(\tilde{q}_j-\hat{q}_j)
$$
$$
[\hat{q}_j,\hat{q}_l]=ik_{jl}
$$
Implies
$$
[\hat{q}_j,\hat{... | {
"domain": "physics.stackexchange",
"id": 10421,
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"openwebmath_score": null,
"tags": "quantum-mechanics, homework-and-exercises, operators, commutator",
"url": null
} |
c++, algorithm, c++17, knapsack-problem
Title: Bin-packing C++ solution using multi-map The need (context).
Several times a day, we need to migrate a set of digital assets from one system to another. The process uses memory (the assets are held in memory for a short time) and we need to do our best to keep the memory ... | {
"domain": "codereview.stackexchange",
"id": 43681,
"lm_label": null,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "c++, algorithm, c++17, knapsack-problem",
"url": null
} |
sign of the second derivative of / indicates whether the graph of y —f{x) is concave upward or concave downward; /* (x) > 0: concave upward / '( x ) < 0: concave downward A point of the curve at which the direction of concavity changes is called a point of inflection (Figure 6.1). To compute the derivative of an expres... | {
"domain": "kotegyesulet.hu",
"id": null,
"lm_label": "1. YES\n2. YES\n\n",
"lm_name": "Qwen/Qwen-72B",
"lm_q1_score": 0.9740426420486938,
"lm_q1q2_score": 0.8116936905018818,
"lm_q2_score": 0.8333245953120233,
"openwebmath_perplexity": 460.81010381349364,
"openwebmath_score": 0.7370645999908447,
"... |
everyday-chemistry
Title: How does a fire start? I know that fire in a few words is the exothermic reaction of a fuel with an oxidizing agent, but I can't fully understand what exactly happens to piece of wood when it is ignited. How do molecules start producing a flame? In other words, what is the chemistry behind th... | {
"domain": "chemistry.stackexchange",
"id": 5678,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "everyday-chemistry",
"url": null
} |
classical-mechanics, kinematics, velocity, angular-velocity
\mathbf{v}_2 = \boldsymbol{\omega}\times\mathbf{r}_2.
$$
Now since the three points are not collinear, we can let
$$
\boldsymbol{\omega} = a\,\mathbf{r}_1 + b\,\mathbf{r}_2
+ c\, \mathbf{r}_1\times\mathbf{r}_2
$$
but we must remember that $\mathbf{r}_1$ and $... | {
"domain": "physics.stackexchange",
"id": 52191,
"lm_label": null,
"lm_name": null,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "classical-mechanics, kinematics, velocity, angular-velocity",
"url": null
} |
c#, excel
//Get the End Column
for (long i = (AccountRow + 1); i <= EndRow; i++)
{
try
{
if (i > EndRow)
break;
Console.WriteLine("Checking ... | {
"domain": "codereview.stackexchange",
"id": 27585,
"lm_label": null,
"lm_name": null,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "c#, excel",
"url": null
} |
homework-and-exercises, general-relativity, differential-geometry, metric-tensor, vector-fields
Title: Understanding the derivation of Killing horizon surface gravity In the book "A Relativist's Toolkit" by Eric Poisson, he explains surface gravity in section 5.2.4
The equation 5.40 says
$$ (-t^\mu t_\mu)_{;\alpha} =... | {
"domain": "physics.stackexchange",
"id": 98810,
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"openwebmath_score": null,
"tags": "homework-and-exercises, general-relativity, differential-geometry, metric-tensor, ... |
human-biology, virology, pathology
Title: Why is rabies incurable? I'm still not sure about the mechanics that lead to rabies being incurable. I know that it can be treated before any symptoms show up, but why is it that once symptoms show the person is a dead man walking? This is because rabies is a viral infection o... | {
"domain": "biology.stackexchange",
"id": 515,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "human-biology, virology, pathology",
"url": null
} |
# Find a generating function.
Find a generating function for the number of selections of sticks of chewing gum chosen from eight flavors if each flavor comes in packet of five sticks.
I am having a bit of an issue with figuring out the logic for the above question. My book provides the solution as $g(x)=(1+x^5+x^{10}... | {
"domain": "stackexchange.com",
"id": null,
"lm_label": "1. YES\n2. YES",
"lm_name": "Qwen/Qwen-72B",
"lm_q1_score": 0.9678992960608886,
"lm_q1q2_score": 0.8001737593938288,
"lm_q2_score": 0.8267117898012104,
"openwebmath_perplexity": 407.5005186697653,
"openwebmath_score": 0.9907031655311584,
"tag... |
Drainboard Sink Faucet, Sg I Bat, Activa 6g Seat Cover, Relion Ear Thermometer Error 1, Cyphenothrin 5 Ec Msds, Bread Cartoon Drawing, Superhero Avatar Creator, | {
"domain": "kiev.ua",
"id": null,
"lm_label": "1. YES\n2. YES\n\n",
"lm_name": "Qwen/Qwen-72B",
"lm_q1_score": 0.9643214491222696,
"lm_q1q2_score": 0.8614374230151711,
"lm_q2_score": 0.8933094081846421,
"openwebmath_perplexity": 1161.597526904899,
"openwebmath_score": 0.5246270895004272,
"tags": nu... |
quantum-mechanics, angular-momentum, group-theory, representation-theory, wigner-eckart
Title: The proof of the Wigner-Eckart theorem for irreducible tensor operators I am reading through Wu-Ki Tung's Group Theory in Physics and I met a problem when going through the part of the Wigner-Eckart theorem for irreducible t... | {
"domain": "physics.stackexchange",
"id": 89695,
"lm_label": null,
"lm_name": null,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "quantum-mechanics, angular-momentum, group-theory, representation-theory, wigner-e... |
java, algorithm, library
As I suggested earlier I want the ending condition to be:
if(current variables are all assigned to false){
stop searching and return
}
We know that the findNextSatisfyingAssignment() will return false and end the while loop when all variables are assigned to false. So we don't need to che... | {
"domain": "codereview.stackexchange",
"id": 25089,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "java, algorithm, library",
"url": null
} |
human-biology, human-anatomy, human-physiology
Title: How can we move our lips even though they don't have any bones? How can we move our lips even though they don't have any bones?
We can move everything if it is attached to the bones. Example: Legs & Arms.
otherwise we can't move it. Because of the Orbicularis ori... | {
"domain": "biology.stackexchange",
"id": 6745,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "human-biology, human-anatomy, human-physiology",
"url": null
} |
python, web-scraping
Title: Web Scraping with Python My target website is Indeed. I tried to implement the scraper such that it is convenient for the end user. I am introducing my code in the readme file on my github repo.
I am somewhat a beginner in programming so I am looking for guidance on things such as if the li... | {
"domain": "codereview.stackexchange",
"id": 37762,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "python, web-scraping",
"url": null
} |
c#, .net
smtp.Send(mail);
Console.WriteLine("Sending {0} mail to:{1}...", title, to);
}
break;
}
catch (SmtpException e)
{
if (i < NumberOfRetriesOnError)
... | {
"domain": "codereview.stackexchange",
"id": 27206,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "c#, .net",
"url": null
} |
homework-and-exercises, newtonian-mechanics, mass
Title: Center of mass confusion my question is basically whether centre of mass is a theoretical concept. As an example, say for a ruler we say that the centre of mass is in the middle and i get that completely, however for something like a ring the centre of mass is i... | {
"domain": "physics.stackexchange",
"id": 39177,
"lm_label": null,
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"lm_q1_score": null,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
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"tags": "homework-and-exercises, newtonian-mechanics, mass",
"url": null
} |
2) Field theory: $\mathbb{Q}(\sqrt{3},\sqrt{5}) = \mathbb{Q}(\sqrt{3})(\sqrt{5})$ has degree $2 \cdot 2=4$ over $\mathbb{Q}$ essentially because $\sqrt{5} \notin \mathbb{Q}(\sqrt{3})$ (easy computation!) and hence $X^2-5$ stays irreducible over $\mathbb{Q}(\sqrt{3})$. So it suffices to prove that $\mathbb{Q}(\sqrt{3},\... | {
"domain": "stackexchange.com",
"id": null,
"lm_label": "1. YES\n2. YES",
"lm_name": "Qwen/Qwen-72B",
"lm_q1_score": 0.972830769252026,
"lm_q1q2_score": 0.8020619258599858,
"lm_q2_score": 0.8244619220634457,
"openwebmath_perplexity": 268.07811686787875,
"openwebmath_score": 0.9289077520370483,
"tag... |
ros, mjpeg-server, tutorials, beginner
Title: About ros_web_video and mjpeg_server
Hello, I know that mjpeg_server is deprecated but for curiosity i was trying to use it whit a turtlebot, I ran the commands as it follows here Wiki for mjpeg and the webpage was loading and not showing the information of the kinect.
... | {
"domain": "robotics.stackexchange",
"id": 20912,
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"lm_name": null,
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"lm_q2_score": null,
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"openwebmath_score": null,
"tags": "ros, mjpeg-server, tutorials, beginner",
"url": null
} |
quantum-field-theory, gauge-theory, quantum-electrodynamics, path-integral, ward-identity
$$Z_3 = \Bigl(1/\bigl(1-\Pi(0)\bigr)\Bigr).$$ We have
$$\tag{9} \bigl(g_{\nu\alpha} - q_{\nu}q_{\alpha}/q^2\bigr) Z_3 \Gamma^{\alpha}(p,q,p+q) = \bigl(g_{\nu\mu} - q_{\nu}q_{\mu}/q^2\bigr)V^{\mu}(p,q,p+q).$$ So we see that the tr... | {
"domain": "physics.stackexchange",
"id": 16856,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
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"openwebmath_score": null,
"tags": "quantum-field-theory, gauge-theory, quantum-electrodynamics, path-integral, ward-i... |
$$\int_{a}^{\infty} \frac{f(x)}{F(x)} \, dx = \log F(\infty) - \log F(a) = \infty$$
where $F$ is an antiderivative of $f$ (which is also positie on $[a, \infty)$. Bringing this idea to discrete setting is not hard. Indeed, when $a_k$'s are positive then you may apply Stolz theorem to
$$\lim_{n\to\infty} \frac{\sum_{k... | {
"domain": "stackexchange.com",
"id": null,
"lm_label": "1. YES\n2. YES",
"lm_name": "Qwen/Qwen-72B",
"lm_q1_score": 0.9805806535200601,
"lm_q1q2_score": 0.8295147880163356,
"lm_q2_score": 0.8459424373085145,
"openwebmath_perplexity": 185.88869333102082,
"openwebmath_score": 0.9335778951644897,
"ta... |
fourier-transform, dtft
Title: Derive DTFT of $x[2n]$ If the DTFT of discrete sequence $x[n]$ is $X(e^{j\omega})$, what is the DTFT of $g[n] = x[2n]$?
I see the textbook answer is
\begin{align*}
G(e^{j\omega}) &= \frac{1}{2} \left( X(e^{j\omega/2}) + X(e^{j(\omega-2\pi)/2}) \right)
\end{align*}
My start of the probl... | {
"domain": "dsp.stackexchange",
"id": 3211,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "fourier-transform, dtft",
"url": null
} |
c, array
inline varray** allocateTDVarray(const int size) {
varray** target = malloc(sizeof(varray*) * (size + 1));
if (VARRAY_DISPLAYDEBUG) {
printf("%s%d\n", "Allocated array of type v_tdvarray with size ", size);
}
target[0] = malloc(sizeof(varray));
target[0][0].size = size;
return ... | {
"domain": "codereview.stackexchange",
"id": 45043,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
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"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "c, array",
"url": null
} |
ISB, NUS, NTU Moderator
Joined: 11 Aug 2016
Posts: 300
Re: What is the value of integer n ? (1) n(n + 1) = 20 (2) 6!/(n!)(6-n)! [#permalink]
### Show Tags
08 Sep 2018, 05:04
vasuca10 wrote:
Option C
As per Statement 1 n*(n+1)=20
Possible values 1*20 , -1*-20, 2*10, -2*-10, 4*5, -4*-5, 5*4, -5*-4, 10*2, -10*-2
Multip... | {
"domain": "gmatclub.com",
"id": null,
"lm_label": "1. Yes\n2. Yes",
"lm_name": "Qwen/Qwen-72B",
"lm_q1_score": 0.9372107878954106,
"lm_q1q2_score": 0.8207970134324674,
"lm_q2_score": 0.8757869884059267,
"openwebmath_perplexity": 6846.832697623608,
"openwebmath_score": 0.5605282783508301,
"tags": n... |
python, python-3.x, pandas
Title: Groupby count, then sum and get the percentage I wrote this code.
It works, but I think there is a more elegant and Pythonic way to this task.
Groupby and count the different occurences
Get the sum of all the occurences
Divide each occurrence by the total of the occurrences and get... | {
"domain": "codereview.stackexchange",
"id": 34995,
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"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "python, python-3.x, pandas",
"url": null
} |
python, algorithm, sorting, bucket-sort
# Put values into buckets.
buckets = [[] for _ in range(N)]
for x in xs:
i = int(N * x)
buckets[i].append(x)
# Sort each bucket.
#
# To keep hammering the point, `b` is a better variable
# name than `bucket` within this tiny, well-defined... | {
"domain": "codereview.stackexchange",
"id": 39300,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "python, algorithm, sorting, bucket-sort",
"url": null
} |
Do we need compactness hypothesis in Lemma 6.2 in Lee's “Introduction to Smooth Manifolds”?
The following lemma is from Lee's "Introduction to Smooth Manifolds."
Lemma 6.2. Suppose $$A\subseteq\mathbb R^n$$ is a compact subset whose intersection with $$\{c\}\times\mathbb R^{n-1}$$ has $$(n-1)$$-dimensional measure ze... | {
"domain": "stackexchange.com",
"id": null,
"lm_label": "1. YES\n2. YES",
"lm_name": "Qwen/Qwen-72B",
"lm_q1_score": 0.9808759604539052,
"lm_q1q2_score": 0.8042136654922933,
"lm_q2_score": 0.8198933381139645,
"openwebmath_perplexity": 85.79743552413981,
"openwebmath_score": 0.9811779260635376,
"tag... |
optics, electromagnetic-radiation, refraction
Title: Why does change in speed of a wave make it refract? When a light wave enters a medium with a higher refractive index (e.g. from air to standard glass) and its speed decreases, why does that make it refract/bend?
I understand that wavelength decreases and frequency s... | {
"domain": "physics.stackexchange",
"id": 18772,
"lm_label": null,
"lm_name": null,
"lm_q1_score": null,
"lm_q1q2_score": null,
"lm_q2_score": null,
"openwebmath_perplexity": null,
"openwebmath_score": null,
"tags": "optics, electromagnetic-radiation, refraction",
"url": null
} |
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