atl_srefsbmv.c

基于Blas CLapck的.用过的人知道是干啥的

/* ---------------------------------------------------------------------
 *
 * -- Automatically Tuned Linear Algebra Software (ATLAS)
 *    (C) Copyright 2000 All Rights Reserved
 *
 * -- ATLAS routine -- Version 3.2 -- December 25, 2000
 *
 * Author         : Antoine P. Petitet
 * Originally developed at the University of Tennessee,
 * Innovative Computing Laboratory, Knoxville TN, 37996-1301, USA.
 *
 * ---------------------------------------------------------------------
 *
 * -- Copyright notice and Licensing terms:
 *
 *  Redistribution  and  use in  source and binary forms, with or without
 *  modification, are  permitted provided  that the following  conditions
 *  are met:
 *
 * 1. Redistributions  of  source  code  must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce  the above copyright
 *    notice,  this list of conditions, and the  following disclaimer in
 *    the documentation and/or other materials provided with the distri-
 *    bution.
 * 3. The name of the University,  the ATLAS group,  or the names of its
 *    contributors  may not be used to endorse or promote products deri-
 *    ved from this software without specific written permission.
 *
 * -- Disclaimer:
 *
 * THIS  SOFTWARE  IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,  INCLUDING,  BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,  INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO,  PROCUREMENT  OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEO-
 * RY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT  (IN-
 * CLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * ---------------------------------------------------------------------
 */
/*
 * Include files
 */
#include "atlas_refmisc.h"
#include "atlas_reflvl2.h"
#include "atlas_reflevel2.h"

void ATL_srefsbmv
(
   const enum ATLAS_UPLO      UPLO,
   const int                  N,
   const int                  K,
   const float                ALPHA,
   const float                * A,
   const int                  LDA,
   const float                * X,
   const int                  INCX,
   const float                BETA,
   float                      * Y,
   const int                  INCY
)
{
/*
 * Purpose
 * =======
 *
 * ATL_srefsbmv performs the matrix-vector operation
 *
 *    y := alpha * A * x + beta * y,
 *
 * where alpha and beta are scalars, x and y are n-element vectors and A
 * is an n by n symmetric band matrix, with k super-diagonals.
 *
 * Arguments
 * =========
 *
 * UPLO    (input)                       const enum ATLAS_UPLO
 *         On entry, UPLO  specifies whether the upper or lower triangu-
 *         lar part of the band matrix A is being supplied as follows:
 *
 *             UPLO = AtlasUpper   The upper triangular part of A is
 *                                 being supplied.
 *
 *             UPLO = AtlasLower   The lower triangular part of A is
 *                                 being supplied.
 *
 *         Unchanged on exit.
 *
 * N       (input)                       const int
 *         On entry, N specifies the order of the matrix A. N must be at
 *         least zero. Unchanged on exit.
 *
 * K       (input)                       const int
 *         On entry, K  specifies  the number of  super-diagonals of the
 *         matrix A. K must satisfy 0 <= K. Unchanged on exit.
 *
 * ALPHA   (input)                       const float
 *         On entry, ALPHA specifies the scalar alpha.   When  ALPHA  is
 *         supplied as zero then  A and X  need not be set on input. Un-
 *         changed on exit.
 *
 * A       (input)                       const float *
 *         On entry,  A  points  to an array of size equal to or greater
 *         than   LDA * n * sizeof(   float   ).    Before  entry   with
 *         UPLO = AtlasUpper, the leading ( k + 1 ) by n part of the ar-
 *         ray  A  must  contain  the  upper triangular band part of the
 *         symmetric matrix, supplied column by column, with the leading
 *         diagonal  of the matrix in row  k of the array, the first su-
 *         per-diagonal starting  at position 1 in row k-1,  and  so on.
 *         The top left k by k triangle of the array  A  is not referen-
 *         ced. Unchanged on exit.
 *         The  following program segment will transfer the upper trian-
 *         gular part  of a symmetric band matrix from conventional full
 *         matrix storage to band storage:
 *
 *            for( j = 0; j < n; j++ )
 *            {
 *               m  = k - j;
 *               for( i = ( m < 0 ? -m : 0 ); i < j; i++ )
 *               {
 *                  a[m+i+j*LDA] = matrix( i, j );
 *               }
 *            }
 *
 *         Before entry with UPLO = AtlasLower, the leading ( k + 1 ) by
 *         n part of  the array A must contain the lower triangular band
 *         part of the symmetric matrix, supplied column by column, with
 *         the leading diagonal of the matrix in row 0 of the array, the
 *         first sub-diagonal starting at position  0  in row  1, and so
 *         on.  The bottom right  k by k  triangle of the array A is not
 *         referenced. Unchanged on exit.
 *         The  following program segment will transfer the lower trian-
 *         gular part  of a symmetric band matrix from conventional full
 *         matrix storage to band storage:
 *
 *            for( j = 0; j < n; j++ )
 *            {
 *               i1 = ( n > j + k + 1 ? j + k + 1 : n );
 *               for( i = j; i < i1; i++ )
 *               {
 *                  a[i-j+j*LDA] = matrix( i, j );
 *               }
 *            }
 *
 *
 * LDA     (input)                       const int
 *         On entry, LDA  specifies the leading dimension of A as decla-
 *         red  in  the  calling (sub) program.  LDA  must  be  at least
 *         k + 1. Unchanged on exit.
 *
 * X       (input)                       const float *
 *         On entry,  X  points to the  first entry to be accessed of an
 *         incremented array of size equal to or greater than
 *            ( 1 + ( n - 1 ) * abs( INCX ) ) * sizeof(   float   ),
 *         that contains the vector x. Unchanged on exit.
 *
 * INCX    (input)                       const int
 *         On entry, INCX specifies the increment for the elements of X.
 *         INCX must not be zero. Unchanged on exit.
 *
 * BETA    (input)                       const float
 *         On entry,  BETA  specifies the scalar  beta.   When  BETA  is
 *         supplied as zero then Y  need not be set on input.  Unchanged
 *         on exit.
 *
 * Y       (input/output)                float *
 *         On entry,  Y  points to the  first entry to be accessed of an
 *         incremented array of size equal to or greater than
 *            ( 1 + ( n - 1 ) * abs( INCY ) ) * sizeof(   float   ),
 *         that contains the vector y.  Before entry with BETA non-zero,
 *         the incremented array  Y  must contain the vector y. On exit,
 *         Y is overwritten by the updated vector y.
 *
 * INCY    (input)                       const int
 *         On entry, INCY specifies the increment for the elements of Y.
 *         INCY must not be zero. Unchanged on exit.
 *
 * ---------------------------------------------------------------------
 */
/* ..
 * .. Executable Statements ..
 *
 */
   if( ( N == 0 ) || ( ( ALPHA == ATL_sZERO ) &&
                       ( BETA  == ATL_sONE  ) ) ) return;
   if( ALPHA == ATL_sZERO ) { Msvscal( N, BETA, Y, INCY ); return; }

   if( UPLO == AtlasUpper )
   {
      ATL_srefsbmvU( N, K, ALPHA, A, LDA, X, INCX, BETA, Y, INCY );
   }
   else
   {
      ATL_srefsbmvL( N, K, ALPHA, A, LDA, X, INCX, BETA, Y, INCY );
   }
/*
 * End of ATL_srefsbmv
 */
}