I should add, that creating M with the Matlab version of my routine causes absolutely no such problem.
Bug when using min() with sparse matrices?
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Hi,
I translated one of my Matlab routines to C and now I've encountered a really strange behaviour which seems to be a bug. M is a sparse matrix and I printed M, M', min(M, M') and min(full(M), full(M')), but all of them as full matrices to see the problem better:
The last matrix is what I want and what I'm supposed to already get by using min(M, M'), but for some reason min(M, M') shows some really weird behaviour. Any gueses what causes this?
Edit: Here's the mex file:
#include "mex.h"
void mexFunction(int nlhs, mxArray* plhs[], int nrhs, const mxArray *prhs[])
{
mxArray *tempArray, *outputDist[1], *inputDist[2], *outputSort[2];
double *tempVal, *pr, *sr, *sorted, *order;
mwSize n, nzmax;
mwIndex *irs, *jcs, i, j, k;
// distance function call
tempArray = mxCreateDoubleMatrix(1, 1, mxREAL);
tempVal = mxGetPr(tempArray);
inputDist[0] = prhs[0];
inputDist[1] = tempArray;
// read input matrix size
n = mxGetN(prhs[0]);
// read real part of input matrix
pr = mxGetPr(prhs[0]);
// read parameter for k
k = (mwIndex)*mxGetPr(prhs[1]);
// create output sparse matrix
nzmax = (mwSize)(n*k);
plhs[0] = mxCreateSparse(n, n, nzmax, mxREAL);
sr = mxGetPr(plhs[0]);
irs = mxGetIr(plhs[0]);
jcs = mxGetJc(plhs[0]);
// go through data points
for (i = 0; i < n; i++)
{
// calculate distance vector
tempVal[0] = (double)(i+1);
mexCallMATLAB(1, outputDist, 2, inputDist, "distEuclidean2");
// sort vector
mexCallMATLAB(2, outputSort, 1, &outputDist[0], "sort");
sorted = mxGetPr(outputSort[0]);
order = mxGetPr(outputSort[1]);
// assign values to sparse matrix
jcs[i] = i*k;
for (j = 0; j < k; j++)
{
irs[i*k+j] = (mwIndex)(order[j]-1);
sr[i*k+j] = sorted[j];
}
}
jcs[n] = n*k;
}
And here is the called distEuclidean2:
function [ d ] = distEuclidean2( M, ii )
d = sqrt(sum((repmat(M(:, ii), 1, size(M, 2)) - M) .^ 2, 1));
emd
6 commentaires
Walter Roberson
le 9 Jan 2012
Suggest you edit the source in to your Question, as comments don't support formatting (or indentation even)
Réponse acceptée
James Tursa
le 9 Jan 2012
Modifié(e) : James Tursa
le 28 Jan 2024
You might try using this to check the matrix:
href=""<http://www.mathworks.com/matlabcentral/fileexchange/20186-spok-checks-if-a-matlab-sparse-matrix-is-ok</a>>
Not sure if it works for 64-bit.
*** EDIT ***
Note that spok has been removed from the FEX. You can use my replacement function sarek instead:
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