Search Results
Search type | Search syntax |
---|---|
Tags | [tag] |
Exact | "words here" |
Author |
user:1234 user:me (yours) |
Score |
score:3 (3+) score:0 (none) |
Answers |
answers:3 (3+) answers:0 (none) isaccepted:yes hasaccepted:no inquestion:1234 |
Views | views:250 |
Code | code:"if (foo != bar)" |
Sections |
title:apples body:"apples oranges" |
URL | url:"*.example.com" |
Saves | in:saves |
Status |
closed:yes duplicate:no migrated:no wiki:no |
Types |
is:question is:answer |
Exclude |
-[tag] -apples |
For more details on advanced search visit our help page |
Numerical algorithms for problems in analysis and algebra, scientific computation
23
votes
Recent observation of gravitational waves
The numbers 36,29,62 were obtained as the best match between the received signals and the output of computer simulations. The 90% confidence intervals on these numbers are about $\pm 4$. The details …
11
votes
Accepted
Well-balanced covering of transpositions in $n$ elements
Close to $n/2$ is possible. I'll do odd $n$ and leave even $n$ for someone else's pleasure.
Let $m=(n-1)/2$. For $i=0,\ldots,n-1$ and $j=1,\ldots,m$, let $M(i,j)$ be the pair $\{i-j,i+j\}$ (all val …
9
votes
Claimed Quadrature Results seem Impossible
I don't know the solution, but the thing that most bothers me about your preprint is the non-explicit nature of Theorem 2 and your inferences from it. Each $O(\,)$ has some "constant" implied in it, …
9
votes
Accelerating convergence for some double sums
Here is a little Maple. Note that using "sum" on the inside causes it to find an algebraic expression for the sum over $\ell$ and using "Sum" on the outside tells it to not try to sum that algebraica …
8
votes
Accepted
How to numerically compute $x \ln x$ and related functions near $0$?
Modern mathematics libraries should be able to find $\log x$ precisely for all floating-point numbers, as the algorithms for doing that have long been known and adopted. My experiments on a fairly rec …
5
votes
Accepted
Error in Polynomial Root Finding Algorithm with Synthetic Division
It is a terrible idea to divide out roots as they are found. There will be examples where the later roots are lost almost completely. See this wikipedia article for a famous and remarkably simple exa …
5
votes
Should computer code be included within publications that present numerical results?
There are some issues that are not emphasised enough in the previous comments and answers. Having the source code used by an author does not let you check that the author's theorems are correct. It on …
4
votes
Degree necessary of a polynomial?
Version 2
Here is some experimental evidence. Like most people here I'm using $-f(x)$ and assuming $0<b<a<1$.
Consider $b=1/100$ and $a=i/100$.
For $2\le i\le 3$, there is a quadratic polynomial.
F …
3
votes
Rapid evaluation of multivariate normal integral
I suggest you try Gauss-Hermite integration. You can guess the precision by increasing the number of abscissae. Tables of abscissae and weights are here.
1
vote
Accepted
Numerical integration of legendre polynomials
It seems fundamentally ill-conditioned.
Since $\int_{-1}^{+1} x^rP_n(x),dx=0$ for $r=0,1,\dots,n-1$, your integral is unchanged if you subtract a polynomial of degree $n-1$ from $f(x)$. I'm guessing …
1
vote
best approximation to the LambertW(x) or exp(LambertW(x))
As Pietro says, $u=\exp(W(x))$ satisfies $u=x/\ln u$. This is a contraction mapping for large enough $u$, so just start with any old approximation, like $u=x/\ln x$, and do $u:=x/\ln u$ until it conv …
0
votes
Numerical evaluation of some series
Maple (2018 edition) can compute this sum numerically quite fast. I don't know the method it uses.
> dP := unapply(diff(binomial(n+k,k),n),n,k);
> Lsum := (k,s) -> evalf(Sum(dP(n,k)/binomial(n+k,k)^ …
0
votes
Quadrature formula max accuracy
Federico's answer gives you the theory. Since you only ask for two abscissae, it is easy to solve this case by first principles. Just put in the abscissae as variables and do the integral. $f(-3^{-1/ …