C Library Functions - sspmv (3)
NAME
sspmv(3f) - [BLAS:SINGLE_BLAS_LEVEL2] SY:=alpha*A*SX+beta*SY, A a packed symmetric matrix.
CONTENTS
Synopsis
Definition
Options
Y
Authors
Further Details
See Also
SYNOPSIS
subroutine sspmv(uplo,n,alpha,ap,x,incx,beta,y,incy)
.. Scalar Arguments .. real,intent(in) :: alpha,beta integer,intent(in) :: incx,incy,n character,intent(in) :: uplo .. .. Array Arguments .. real,intent(in) :: ap(*),x(*) real,intent(inout) :: y(*) ..
DEFINITION
SSPMV 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.
OPTIONS
UPLO
UPLO is CHARACTER*1 On entry, UPLO specifies whether the upper or lower triangular part of the matrix A is supplied in the packed array AP as follows:
UPLO = ’U’ or ’u’ The upper triangular part of A is supplied in AP.UPLO = ’L’ or ’l’ The lower triangular part of A is supplied in AP.
N
N is INTEGER On entry, N specifies the order of the matrix A. N must be at least zero.
ALPHA
ALPHA is REAL On entry, ALPHA specifies the scalar alpha.
AP
AP is REAL array, dimension at least ( ( n*( n + 1 ) )/2 ). Before entry with UPLO = ’U’ or ’u’, the array AP must contain the upper triangular part of the symmetric matrix packed sequentially, column by column, so that AP( 1 ) contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 ) and a( 2, 2 ) respectively, and so on. Before entry with UPLO = ’L’ or ’l’, the array AP must contain the lower triangular part of the symmetric matrix packed sequentially, column by column, so that AP( 1 ) contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 ) and a( 3, 1 ) respectively, and so on.
X
X is REAL array, dimension at least ( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented array X must contain the n element vector x.
INCX
INCX is INTEGER On entry, INCX specifies the increment for the elements of X. INCX must not be zero.
BETA
BETA is REAL On entry, BETA specifies the scalar beta. When BETA is supplied as zero then Y need not be set on input.
Y
Y is REAL array, dimension at least ( 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
INCY is INTEGER On entry, INCY specifies the increment for the elements of Y. INCY must not be zero.
AUTHORS
o Univ. of Tennessee o Univ. of California Berkeley o Univ. of Colorado Denver o NAG Ltd. date:December 2016
FURTHER DETAILS
Level 2 Blas routine. The vector and matrix arguments are not referenced when N = 0, or M = 0
-- Written on 22-October-1986. Jack Dongarra, Argonne National Lab. Jeremy Du Croz, Nag Central Office. Sven Hammarling, Nag Central Office. Richard Hanson, Sandia National Labs.
SEE ALSO
Online html documentation available at http://www.netlib.org/lapack/explore-html/
| Nemo Release 3.1 | sspmv (3) | July 22, 2023 |
