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* Contents: Native C interface to LAPACK utility function
* Author: Intel Corporation
* Created in February, 2010
*****************************************************************************/
#include "lapacke_utils.h"

/* Check a matrix for NaN entries. */

lapack_logical LAPACKE_dtf_nancheck( int matrix_layout, char transr,
                                      char uplo, char diag,
                                      lapack_int n,
                                      const double *a )
{
    lapack_int len;
    lapack_logical rowmaj, ntr, lower, unit;
    lapack_int n1, n2, k;

    if( a == NULL ) return (lapack_logical) 0;

    rowmaj = (matrix_layout == LAPACK_ROW_MAJOR);
    ntr    = LAPACKE_lsame( transr, 'n' );
    lower  = LAPACKE_lsame( uplo,   'l' );
    unit   = LAPACKE_lsame( diag,   'u' );

    if( ( !rowmaj && ( matrix_layout != LAPACK_COL_MAJOR ) ) ||
        ( !ntr    && !LAPACKE_lsame( transr, 't' )
                  && !LAPACKE_lsame( transr, 'c' ) ) ||
        ( !lower  && !LAPACKE_lsame( uplo,   'u' ) ) ||
        ( !unit   && !LAPACKE_lsame( diag,   'n' ) ) ) {
        /* Just exit if any of input parameters are wrong */
        return (lapack_logical) 0;
    }

    if( unit ) {
        /* Unit case, diagonal should be excluded from the check for NaN.
         * Decoding RFP and checking both triangulars and rectangular
         * for NaNs.
         */
        if( lower ) {
            n2 = n / 2;
            n1 = n - n2;
        } else {
            n1 = n / 2;
            n2 = n - n1;
        }
        if( n % 2 == 1 ) {
            /* N is odd */
            if( ( rowmaj || ntr ) && !( rowmaj && ntr ) ) {
                /* N is odd and ( TRANSR = 'N' .XOR. ROWMAJOR) */
                if( lower ) {
                    return LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'l', 'u',
                                                 n1, &a[0], n )
                        || LAPACKE_dge_nancheck( LAPACK_ROW_MAJOR, n2, n1,
                                                 &a[n1], n )
                        || LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'u', 'u',
                                                 n2, &a[n], n );
                } else {
                    return LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'l', 'u',
                                                 n1, &a[n2], n )
                        || LAPACKE_dge_nancheck( LAPACK_ROW_MAJOR, n1, n2,
                                                 &a[0], n )
                        || LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'u', 'u',
                                                 n2, &a[n1], n );
                }
            } else {
                /* N is odd and
                   ( ( TRANSR = 'C' || TRANSR = 'T' ) .XOR. COLMAJOR ) */
                if( lower ) {
                    return LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'u', 'u',
                                                 n1, &a[0], n1 )
                        || LAPACKE_dge_nancheck( LAPACK_ROW_MAJOR, n1, n2,
                                                 &a[1], n1 )
                        || LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'l', 'u',
                                                 n2, &a[1], n1 );
                } else {
                    return LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'u', 'u',
                                                 n1, &a[(size_t)n2*n2], n2 )
                        || LAPACKE_dge_nancheck( LAPACK_ROW_MAJOR, n2, n1,
                                                 &a[0], n2 )
                        || LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'l', 'u',
                                                 n2, &a[(size_t)n1*n2], n2 );
                }
            }
        } else {
            /* N is even */
            k = n / 2;
            if( ( rowmaj || ntr ) && !( rowmaj && ntr ) ) {
                /* N is even and ( TRANSR = 'N' .XOR. ROWMAJOR) */
                if( lower ) {
                    return LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'l', 'u',
                                                 k, &a[1], n+1 )
                        || LAPACKE_dge_nancheck( LAPACK_ROW_MAJOR, k, k,
                                                 &a[k+1], n+1 )
                        || LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'u', 'u',
                                                 k, &a[0], n+1 );
                } else {
                    return LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'l', 'u',
                                                 k, &a[k+1], n+1 )
                        || LAPACKE_dge_nancheck( LAPACK_ROW_MAJOR, k, k,
                                                 &a[0], n+1 )
                        || LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'u', 'u',
                                                 k, &a[k], n+1 );
                }
            } else {
                /* N is even and
                   ( ( TRANSR = 'C' || TRANSR = 'T' ) .XOR. COLMAJOR ) */
                if( lower ) {
                    return LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'u', 'u',
                                                 k, &a[k], k )
                        || LAPACKE_dge_nancheck( LAPACK_ROW_MAJOR, k, k,
                                                 &a[(size_t)k*(k+1)], k )
                        || LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'l', 'u',
                                                 k, &a[0], k );
                } else {
                    return LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'u', 'u',
                                                 k, &a[(size_t)k*(k+1)], k )
                        || LAPACKE_dge_nancheck( LAPACK_ROW_MAJOR, k, k,
                                                 &a[0], k )
                        || LAPACKE_dtr_nancheck( LAPACK_ROW_MAJOR, 'l', 'u',
                                                 k, &a[(size_t)k*k], k );
                }
            }
        }
    } else {
        /* Non-unit case - just check whole array for NaNs. */
        len = n*(n+1)/2;
        return LAPACKE_dge_nancheck( LAPACK_COL_MAJOR, len, 1, a, len );
    }
}
