dspmv(3P) Sun Performance Library dspmv(3P)NAMEdspmv - perform the matrix-vector operation y := alpha*A*x + beta*y
SYNOPSIS
SUBROUTINE DSPMV(UPLO, N, ALPHA, A, X, INCX, BETA, Y, INCY)
CHARACTER * 1 UPLO
INTEGER N, INCX, INCY
DOUBLE PRECISION ALPHA, BETA
DOUBLE PRECISION A(*), X(*), Y(*)
SUBROUTINE DSPMV_64(UPLO, N, ALPHA, A, X, INCX, BETA, Y, INCY)
CHARACTER * 1 UPLO
INTEGER*8 N, INCX, INCY
DOUBLE PRECISION ALPHA, BETA
DOUBLE PRECISION A(*), X(*), Y(*)
F95 INTERFACE
SUBROUTINE SPMV(UPLO, N, ALPHA, A, X, [INCX], BETA, Y, [INCY])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, INCX, INCY
REAL(8) :: ALPHA, BETA
REAL(8), DIMENSION(:) :: A, X, Y
SUBROUTINE SPMV_64(UPLO, N, ALPHA, A, X, [INCX], BETA, Y, [INCY])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, INCX, INCY
REAL(8) :: ALPHA, BETA
REAL(8), DIMENSION(:) :: A, X, Y
C INTERFACE
#include <sunperf.h>
void dspmv(char uplo, int n, double alpha, double *a, double *x, int
incx, double beta, double *y, int incy);
void dspmv_64(char uplo, long n, double alpha, double *a, double *x,
long incx, double beta, double *y, long incy);
PURPOSEdspmv 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 matrix, supplied in packed form.
ARGUMENTS
UPLO (input)
On entry, UPLO specifies whether the upper or lower triangu‐
lar part of the matrix A is supplied in the packed array A as
follows:
UPLO = 'U' or 'u' The upper triangular part of A is sup‐
plied in A.
UPLO = 'L' or 'l' The lower triangular part of A is sup‐
plied in A.
Unchanged on exit.
N (input)
On entry, N specifies the order of the matrix A. N >= 0.
Unchanged on exit.
ALPHA (input)
On entry, ALPHA specifies the scalar alpha. Unchanged on
exit.
A (input)
( ( n*( n + 1 ) )/2 ). Before entry with UPLO = 'U' or 'u',
the array A must contain the upper triangular part of the
symmetric matrix packed sequentially, column by column, so
that A( 1 ) contains a( 1, 1 ), A( 2 ) and A( 3 ) contain a(
1, 2 ) and a( 2, 2 ) respectively, and so on. Before entry
with UPLO = 'L' or 'l', the array A must contain the lower
triangular part of the symmetric matrix packed sequentially,
column by column, so that A( 1 ) contains a( 1, 1 ), A( 2 )
and A( 3 ) contain a( 2, 1 ) and a( 3, 1 ) respectively, and
so on. Unchanged on exit.
X (input)
( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented
array X must contain the n element vector x. Unchanged on
exit.
INCX (input)
On entry, INCX specifies the increment for the elements of X.
INCX <> 0. Unchanged on exit.
BETA (input)
On entry, BETA specifies the scalar beta. When BETA is sup‐
plied as zero then Y need not be set on input. Unchanged on
exit.
Y (input/output)
( 1 + ( n - 1 )*abs( INCY ) ). Before entry, the incremented
array Y must contain the n element vector y. On exit, Y is
overwritten by the updated vector y.
INCY (input)
On entry, INCY specifies the increment for the elements of Y.
INCY <> 0. Unchanged on exit.
6 Mar 2009 dspmv(3P)
