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Questions tagged [numerical]

This tag is for questions concerning problems using numbers which either cannot be exactly solved, or where the exact solution may be much more difficult to acquire than by using numerical methods.

This tag is for questions concerning problems using numbers which either cannot be exactly solved, or where the exact solution may be much more difficult to acquire than by using numerical methods.

It includes questions about algorithms, precision and accuracy of underlying numbers, advantages and disadvantages of several methods, error propagation, problems with the underlying numbers and data structures.

508 questions
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Numeric Keyboard?

I have several instances in my application that I would prefer to use a numerical keyboard. Does one exist in WP7 and if so, how would I go about popping that one up for a text box instead of the normal one?
Hosemeyer
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How do the Sho dll's from Microsoft Research compare to the open-source Math.NET numerics project

I'm considering Sho from the perspective of developing general .NET applications and something that has been difficult for me in the past is that there is NO standard math library for the .NET platform. Aside from the commercial implementations, two…
Sam
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LU Decomposition from Numerical Recipes not working; what am I doing wrong?

I've literally copied and pasted from the supplied source code for Numerical Recipes for C for in-place LU Matrix Decomposition, problem is its not working. I'm sure I'm doing something stupid but would appreciate anyone being able to point me in…
Bolster
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how does numpy.linalg.eigh vs numpy.linalg.svd?

problem description For a square matrix, one can obtain the SVD X= USV' decomposition, by using simply numpy.linalg.svd u,s,vh = numpy.linalg.svd(X) routine or numpy.linalg.eigh, to compute the eig decomposition on Hermitian matrix X'X and…
ArtificiallyIntelligence
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Java / Scala math library with elliptic integrals and bessel functions?

I am looking for a math library for scientific computing to use in Java / Scala. Especially I need complete elliptic integrals und modified Bessel functions. I would be nice if it is open source, but I guess I will have to take whatever is out…
Radfahrer
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UMFPACK and BOOST's uBLAS Sparse Matrix

I am using Boost's uBLAS in a numerical code and have a 'heavy' solver in place: http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?LU_Matrix_Inversion The code works excellently, however, it is painfully slow. After some research, I…
ccook
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Code to solve determinant using Python without using scipy.linalg.det

Description(this is a hwk question): I am not sure where to start here. I plan to use Laplace's Expansion but I am not sure how to implement it for nxn matrices. Any help would be appreciated. Note: I already have a function to generate random…
theAngryPhysicist
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Numerical problems in Matlab: Same input, same code -> different output?

I am experiencing problems when I compare results from different runs of my Matlab software with the same input. To narrow the problem, I did the following: save all relevant variables using Matlab's save() method call a method which calculates…
Philipp
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n-dimensional integration in R with limits as functions

I'm aware of R packages such as cubature which are able to perform numerical integration for many integrals. However, in my situation the limits of integration are not integers, but functions of the other variables. For instance, suppose I have…
nathanesau
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Bizarre numerical errors

I am implementing a simple two-state particle filter. If you don't know what a particle filter is, that's fine - the short version is that I need to compute weighted means with weights between 0 and 1, and values between 0 and 1. Each particle has…
user650261
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Numerical bug in intersecting the equation of ray and torus when the camera is far from the torus

I am trying to ray trace a torus without triangulating the torus and just by intersecting the ray and torus analytic equation. I did that with the following code: void circularTorusIntersectFunc(const CircularTorus* circularToruses, RTCRay& ray,…
mmostajab
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Numerical Pattern Matching

A project I'm researching requires some numerical pattern matching. My searches haven't turned up many relevant hits since most results tend to be around text pattern matching. The idea is we'll have certain wave patterns we'll need to be watching…
Timothy Strimple
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Error at lapack cgesv when matrix is not singular

This is my first post. I usually ask classmates for help, but they have a lot of work now and I'm too desperate to figure this out on my own :). I am working on a project for school and I have come to a point where I need to solve a system of linear…
Jan Malec
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Numerical derivative of a vector

I have a problem with numerical derivative of a vector that is x: Nx1 with respect to another vector t (time) that is the same size of x. I do the following (x is chosen to be sine function as an example): t=t0:ts:tf; x=sin(t); xd=diff(x)/ts; but…
milad
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convolution of positively supported functions in R

I want the convolution of two functions defined on [0,Inf), say f=function(x) (1+0.5*cos(2*pi*x))*(x>=0) and g=function(x) exp(-2*x)*(x>0) Using the integrate function of R I can do this, cfg=function(x) integrate(function(y)…
user3667365
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