bugGNU Scientific Library - Bugs: bug #53904, Bug gsl_matrix_complex_set

 
 

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bug #53904: Bug gsl_matrix_complex_set

Submitted by:  Patrick Alken <psa>
Submitted on:  Mon 14 May 2018 09:39:47 PM UTC  
 
Category:  None Severity:  3 - Normal
Operating System:  Status:  None
Assigned to:  None Open/Closed:  Open
Release: 

Mon 14 May 2018 09:39:47 PM UTC, original submission:

from daniel =dot= comparat =at= u-psud =dot= fr

Dear sir or Madam

I found a bug when using gsl_matrix_complex_set.

You will find the code below, the output of the data array is wrong if I use

/gsl_matrix_complex_set(m, 1, 1, gsl_complex_rect(1., 0.))/

in the code. So there is a bug. However if using

/gsl_complex x = gsl_complex_rect(1., 0.);/

/ gsl_matrix_complex_set(m, 1, 1, x);/

it is O.K.

Here is a code (I was testing using a real matrix the complex eigenvalue)

#include <iostream>
#include <fstream>
#include <iomanip>
#include <cmath>
#include <string>
#include <stdio.h> /* printf */
#include <stdlib.h> /* system, NULL, EXIT_FAILURE */
#include <gsl/gsl_math.h>
#include <gsl/gsl_eigen.h>
#include <gsl/gsl_matrix.h>
#include <gsl/gsl_vector.h>
#include <gsl/gsl_complex.h>
#include <gsl/gsl_complex_math.h>
#include <gsl/gsl_eigen.h>
#include <gsl/gsl_linalg.h>
#include <gsl/gsl_blas.h>
#include <gsl/gsl_cblas.h>

using namespace std;

int main()
{

double S_VN =0. ;
int size = 4;
cout << " size = " << size << endl;
double data[16] = { -1.0, 1.0, -1.0, 1.0,
-8.0, 4.0, -2.0, 1.0,
27.0, 9.0, 3.0, 1.0,
64.0, 16.0, 4.0, 1.0
};

for (int i=0; i<16; i++)
cout << " i = " << i << " data[i] " << data[i] << endl;

gsl_eigen_herm_workspace *w = gsl_eigen_herm_alloc(size); // This function allocates a workspace for computing eigenvalues
gsl_matrix_complex *m = gsl_matrix_complex_alloc(size, size);
gsl_vector *eval = gsl_vector_alloc (size); // Valeurs propres

gsl_complex x = gsl_complex_rect(1., 0.);

for (int i=0; i<4; i++)
for (int j=0; j<4; j++)
{
cout << " i = " << i << " j = " << j << " j+4*i = " << j+4*i << " data[i][j] " << data[j+4*i] << " data [9] " << data[9] << endl;
gsl_matrix_complex_set(m, 1, 1, x); // matrice pour rho_gg = rho_11
}
gsl_eigen_herm(m, eval, w); // This function computes the eigenvalues of the complex hermitian matrix
gsl_eigen_herm_free(w); // This function frees the memory associated with the workspace w.

return 1;
}

Patrick Alken <psa>
Project Administrator

 

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