From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Varghese John" <vjohn111@hotmail.com>
To: Jim.Love@asml.com, gsl-discuss@sources.redhat.com
Subject: Re: Eigen value problem
Date: Wed, 19 Dec 2001 13:20:00 -0000
Message-id: <F199sNPw3770cjHRY1J0000fa3f@hotmail.com>
X-SW-Source: 2001/msg00541.html

Thank you for your prompt reply.
I just switched to gsl 9.2+
and the problem disappeared!
Was this a known issue?

Anyway, thank you for the prompt reply.

Regards,
John

>From: "Jim Love" <Jim.Love@asml.com>
>To: <vjohn111@hotmail.com>, <gsl-discuss@sources.redhat.com>
>Subject: Re: Eigen value problem
>Date: Mon, 01 Oct 2001 12:30:06 -0400
>
>This program works for me just fine (gsl 0.9.2 on win32 and redhat 7.1).  
>Here is the output for a 2x2 and a 3x3:
>
>The Input Matrix:
>      1       2
>      2       1
>
>The EigenValues :
>eigenvalue = 3
>eigenvalue = -1
>
>The Input Matrix:
>      4       1       1
>      1       2       2
>      1       2       9
>
>The EigenValues :
>eigenvalue = 9.79216
>eigenvalue = 3.93673
>eigenvalue = 1.27111
>
>James A. Love
>X4477
>Pager 1-800-286-1188 Pin# 400659
>
> >>> "Varghese John" <vjohn111@hotmail.com> 10/01/01 11:51AM >>>
>
>Hi,
>I am having problems with the following program.
>trying to get eigen values for the 2x2 matrix, and the program hangs?
>
>--it works fine for a 3x3 matrix!
>
>thanks.
>vj
>-----------------------------------------------
>#include <gsl/gsl_eigen.h>
>#include <stdio.h>
>#include <math.h>
>
>#define TestSize 2
>
>void GetEigen1();
>void GetEigenvaluesForSymmMat(  gsl_matrix * m, int mSize, gsl_vector * v);
>
>
>int main(){
>	GetEigen1();
>	return(0);
>}
>
>void GetEigen1(){
>
>   int i;
>   int j;
>   int x;
>
>   gsl_matrix * m = gsl_matrix_alloc(TestSize, TestSize);
>   gsl_matrix_set_zero(m);
>
>
>   /* matrix = ((1, 2), (2, 1)) */
>
>   gsl_matrix_set(m, 0, 0, 1.0);
>   gsl_matrix_set(m, 0, 1, 2.0);
>   gsl_matrix_set(m, 1, 0, 2.0);
>   gsl_matrix_set(m, 1, 1, 1.0);
>
>
>
>   /* matrix = ((4, 1, 1), (1, 2, 2), (1, 2, 9)) */
>   /*
>   gsl_matrix_set(m, 0, 0, 4.0);
>   gsl_matrix_set(m, 0, 1, 1.0);
>   gsl_matrix_set(m, 0, 2, 1.0);
>   gsl_matrix_set(m, 1, 0, 1.0);
>   gsl_matrix_set(m, 1, 1, 2.0);
>   gsl_matrix_set(m, 1, 2, 2.0);
>   gsl_matrix_set(m, 2, 0, 1.0);
>   gsl_matrix_set(m, 2, 1, 2.0);
>   gsl_matrix_set(m, 2, 2, 9.0);
>   */
>
>
>   printf("The Input Matrix: \n");
>   for (i = 0; i < TestSize; i++){
>	  for (j = 0; j <TestSize; j++){
>       printf("%6.4g \t", gsl_matrix_get (m, i, j));
>	  }
>     printf("\n");
>   }
>   printf("\n");
>
>   //use this vector to store the eigen values.
>   gsl_vector *v=gsl_vector_alloc(TestSize);
>     GetEigenvaluesForSymmMat( m, TestSize, v);
>     printf("The EigenValues : \n");
>
>   //print the result
>     for (x = 0; x < TestSize; x++)
>      {
>         printf("eigenvalue = %g\n", gsl_vector_get(v, x));
>       }
>}
>
>
>//This function computes the eigen values of a symmetric block
>//and returns the ordered eigen values in the vector v.
>
>void GetEigenvaluesForSymmMat(  gsl_matrix * m, int mSize, gsl_vector * v) 
>{
>
>   gsl_vector *eval = gsl_vector_alloc (mSize);
>     gsl_vector_set_zero(eval);
>   gsl_matrix *evec = gsl_matrix_alloc (mSize, mSize);
>     gsl_matrix_set_zero(evec);
>   gsl_eigen_symmv_workspace * w =
>     gsl_eigen_symmv_alloc (mSize);
>
>   gsl_eigen_symmv (m, eval, evec, w);
>
>   gsl_eigen_symmv_free(w);
>
>   gsl_eigen_symmv_sort (eval, evec, GSL_EIGEN_SORT_ABS_DESC);
>
>   gsl_vector_memcpy(v, eval);
>
>}
>
>
>
>
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