lapacke_dbbcsd_work.c

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* Contents: Native middle-level C interface to LAPACK function dbbcsd
* Author: Intel Corporation
*****************************************************************************/
 
#include "lapacke_utils.h"
 
lapack_int LAPACKE_dbbcsd_work( int matrix_layout, char jobu1, char jobu2,
                                char jobv1t, char jobv2t, char trans,
                                lapack_int m, lapack_int p, lapack_int q,
                                double* theta, double* phi, double* u1,
                                lapack_int ldu1, double* u2, lapack_int ldu2,
                                double* v1t, lapack_int ldv1t, double* v2t,
                                lapack_int ldv2t, double* b11d, double* b11e,
                                double* b12d, double* b12e, double* b21d,
                                double* b21e, double* b22d, double* b22e,
                                double* work, lapack_int lwork )
{
    lapack_int info = 0;
    /* LAPACK function works with matrices in both layouts. It is supported
     * through TRANS parameter. So all conversion between layouts can be
     * completed in LAPACK function. See the table below which describes how
     * every LAPACKE call is forwarded to corresponding LAPACK call.
     *
     *   matrix_layout    | trans_LAPACKE | -> trans_LAPACK
     *                    |   (trans)     |       (ltrans)
     *   -----------------+---------------+----------------
     *   LAPACK_COL_MAJOR |     'N'       | ->     'N'
     *   LAPACK_COL_MAJOR |     'T'       | ->     'T'
     *   LAPACK_ROW_MAJOR |     'N'       | ->     'T'
     *   LAPACK_ROW_MAJOR |     'T'       | ->     'T'
     *       (note that for row major layout trans parameter is ignored)
     */
    if( matrix_layout == LAPACK_COL_MAJOR ||
        matrix_layout == LAPACK_ROW_MAJOR ) {
        char ltrans;
        if( !LAPACKE_lsame( trans, 't' ) && matrix_layout == LAPACK_COL_MAJOR ) {
            ltrans = 'n';
        } else {
            ltrans = 't';
        }
        /* Call LAPACK function and adjust info */
        LAPACK_dbbcsd( &jobu1, &jobu2, &jobv1t, &jobv2t, &ltrans, &m, &p, &q,
                       theta, phi, u1, &ldu1, u2, &ldu2, v1t, &ldv1t, v2t,
                       &ldv2t, b11d, b11e, b12d, b12e, b21d, b21e, b22d, b22e,
                       work, &lwork, &info );
        if( info < 0 ) {
            info = info - 1;
        }
    } else {
        info = -1;
        LAPACKE_xerbla( "LAPACKE_dbbcsd_work", info );
    }
    return info;
}