Band matrix storage issue

Band matrix storage issue

I get wrong result while computing eigenvalues of a symmetric matrix in band storage using LAPACK routine "dsbev".
Here is code example. Consider matrix A=E. A is in band storage AB with one additional zero super-diagonal.

#include "include/mkl.h"
#define N 4

int main() {
double AB[2][N]={0,0,0,0,1,1,1,1};
int n=N;
int ldab=2;
int kd=1;
int lwork=3*N;
int ldz=1;
int info;
double work[3*N];
double w[N];
double z[1];
dsbev ("N", "U", &n, &kd, *AB, &ldab, w, z, &ldz, work, &info);

printf( "Eigenvalues: %g %g %g %g
", w[0], w[1], w[2], w[3]);
return 0;

The solution of MKL is:
-0.801938 0 0.554958 2.24698
But as we all know correct result is 1 1 1 1
What's wrong here?

Thank you.

Message Edited by on 12-13-2004 06:50 PM

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Sorry for stupid question, just woke up with fresh head and fixed it

Glad we could help :-) --Bruce

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