sspr2 (3)  Linux Man Pages
NAME
sspr2.f 
SYNOPSIS
Functions/Subroutines
subroutine sspr2 (UPLO, N, ALPHA, X, INCX, Y, INCY, AP)
SSPR2
Function/Subroutine Documentation
subroutine sspr2 (characterUPLO, integerN, realALPHA, real, dimension(*)X, integerINCX, real, dimension(*)Y, integerINCY, real, dimension(*)AP)
SSPR2 Purpose:

SSPR2 performs the symmetric rank 2 operation A := alpha*x*y**T + alpha*y*x**T + A, where alpha is a scalar, 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.
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.
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.
INCYINCY is INTEGER On entry, INCY specifies the increment for the elements of Y. INCY must not be zero.
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. On exit, the array AP is overwritten by the upper triangular part of the updated matrix. 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. On exit, the array AP is overwritten by the lower triangular part of the updated matrix.
Author:

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

Level 2 Blas routine.  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 143 of file sspr2.f.
Author
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