sspmv (3)  Linux Manuals
NAME
sspmv.f 
SYNOPSIS
Functions/Subroutines
subroutine sspmv (UPLO, N, ALPHA, AP, X, INCX, BETA, Y, INCY)
SSPMV
Function/Subroutine Documentation
subroutine sspmv (characterUPLO, integerN, realALPHA, real, dimension(*)AP, real, dimension(*)X, integerINCX, realBETA, real, dimension(*)Y, integerINCY)
SSPMV Purpose:

SSPMV performs the matrixvector 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.
Parameters:

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.
NN is INTEGER On entry, N specifies the order of the matrix A. N must be at least zero.
ALPHAALPHA is REAL On entry, ALPHA specifies the scalar alpha.
APAP is REAL array of 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.
XX is REAL array of dimension at least ( 1 + ( n  1 )*abs( INCX ) ). Before entry, the incremented array X must contain the n element vector x.
INCXINCX is INTEGER On entry, INCX specifies the increment for the elements of X. INCX must not be zero.
BETABETA is REAL On entry, BETA specifies the scalar beta. When BETA is supplied as zero then Y need not be set on input.
YY is REAL array of 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.
INCYINCY is INTEGER On entry, INCY specifies the increment for the elements of Y. INCY must not be zero.
Author:

Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
 November 2011
Further Details:

Level 2 Blas routine. The vector and matrix arguments are not referenced when N = 0, or M = 0  Written on 22October1986. Jack Dongarra, Argonne National Lab. Jeremy Du Croz, Nag Central Office. Sven Hammarling, Nag Central Office. Richard Hanson, Sandia National Labs.
Definition at line 148 of file sspmv.f.
Author
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