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Ch LAPACK for C LAPACK bindings
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Ch Professional Edition supports all C LAPACK functions.
<![CDATA[
/*
This C program uses C LAPACK function dgeev_() to calculate
engenvalues in double data type. The program is readily run in Ch
interpretively without compilation.
*/
#include <stdio.h>
#include <f2c.h>
#define SIZE 3
int main( ) {
char jobvl = 'V';
char jobvr = 'N';
long int n = SIZE;
double a[SIZE][SIZE] = {1., 3., 1., 0., 4., 5., 0., 0., 9.};
long int lda = SIZE;
double wr[SIZE];
double wi[SIZE];
double vl[3*SIZE];
long int ldvl = SIZE;
double vr[3*SIZE];
long int ldvr = SIZE;
double work[4*SIZE];
long int lwork = 4*SIZE;
long int info;
double b[3][3];
int i, j, nn=3, mm = 3;
for(i=0; i<nn; i++)
for(j=0; j<mm; j++)
b[i][j] = a[j][i];
/* Subroutine int dgeev_(char *jobvl, char *jobvr, integer *n, real *a,
integer *lda, real *wr, real *wi, real *vl, integer *ldvl, real *vr,
integer *ldvr, real *work, integer *lwork, integer *info)
*/
dgeev_(&jobvl, &jobvr, &n, b, &lda, wr, wi, vl, &ldvl, vr, &ldvr, work,
&lwork, &info);
printf(" INFO=%d\n", info );
for ( i= 0; i< SIZE; i++ ) {
printf("WR[ %d ] = %f\n", i, wr[ i ]);
}
return 0;
}
]]>
The output is:
INFO=0
WR[ 0 ] = 1.000000
WR[ 1 ] = 4.000000
WR[ 2 ] = 9.000000
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