topic Re: Find eigenvalues and eigenvectors in Intel® oneAPI Math Kernel Library

Find eigenvalues and eigenvectors

anacondgame — Mon, 02 Jul 2007 09:34:10 GMT

I Have a 8x8 symmetric matrix A and I wont compute the eigenvalues and eigenvectors with dsyevd function.

The parameter are following:

...
// Var dichiaration

job = 'V';

uplo = 'L';

n = 8;

lda = 8;

lwork = 3*pow(n,2)+(5+2*3)*n+1;

liwork = 5*n+2;

// alloc the vectors

work = (double*)calloc(lwork,sizeof(double));

w = (double*)calloc(n,sizeof(double));

iwork = (int*)calloc(liwork,sizeof(int));

// call dsyevd for compute the eigenvalues and eigenvectors

dsyevd(&job,&uplo,&n,A,&lda,w,work,&lwork,iwork,&liwork,&info);
...

but the output program is incorrect !!? why?
help me, please!!!

Re: Find eigenvalues and eigenvectors

Zhanghong_T_ — Mon, 02 Jul 2007 09:45:57 GMT

(float *)--->(double *)

dsyevd--->ssyevd

Re: Find eigenvalues and eigenvectors

anacondgame — Mon, 02 Jul 2007 09:54:05 GMT

sorry, I have been wrong to write...
but the problem remains!

Re: Find eigenvalues and eigenvectors

anacondgame — Mon, 02 Jul 2007 13:09:16 GMT

the "A" matrix is a two-dimensional or one-dimensional array?

A = (double**)malloc(n*double*);

for(i=0; i

  A=(double*)calloc(n,sizeof(double));

A = (double*)calloc(n,sizeof(double));

where n = 8 ?????

Re: Find eigenvalues and eigenvectors

TimP — Mon, 02 Jul 2007 13:25:57 GMT

It's a 2-dimensional Fortran array, not a **.

Re: Find eigenvalues and eigenvectors

Intel_C_Intel — Mon, 02 Jul 2007 16:55:49 GMT

You can declare an array in C of size n*n of type double for !, and be sure to load in in Fortran style, i.e., column order, as I had stated in an earlier response.

lda will be set to n in this case.

Bruce