DSYR2 (3)  Linux Manuals
NAME
dsyr2.f 
SYNOPSIS
Functions/Subroutines
subroutine dsyr2 (UPLO, N, ALPHA, X, INCX, Y, INCY, A, LDA)
DSYR2
Function/Subroutine Documentation
subroutine dsyr2 (characterUPLO, integerN, double precisionALPHA, double precision, dimension(*)X, integerINCX, double precision, dimension(*)Y, integerINCY, double precision, dimension(lda,*)A, integerLDA)
DSYR2 Purpose:

DSYR2 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.
Parameters:

UPLO
UPLO is CHARACTER*1 On entry, UPLO specifies whether the upper or lower triangular part of the array A is to be referenced as follows: UPLO = 'U' or 'u' Only the upper triangular part of A is to be referenced. UPLO = 'L' or 'l' Only the lower triangular part of A is to be referenced.
NN is INTEGER On entry, N specifies the order of the matrix A. N must be at least zero.
ALPHAALPHA is DOUBLE PRECISION. On entry, ALPHA specifies the scalar alpha.
XX is DOUBLE PRECISION 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 DOUBLE PRECISION 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.
AA is DOUBLE PRECISION array of DIMENSION ( LDA, n ). Before entry with UPLO = 'U' or 'u', the leading n by n upper triangular part of the array A must contain the upper triangular part of the symmetric matrix and the strictly lower triangular part of A is not referenced. On exit, the upper triangular part of the array A is overwritten by the upper triangular part of the updated matrix. Before entry with UPLO = 'L' or 'l', the leading n by n lower triangular part of the array A must contain the lower triangular part of the symmetric matrix and the strictly upper triangular part of A is not referenced. On exit, the lower triangular part of the array A is overwritten by the lower triangular part of the updated matrix.
LDALDA is INTEGER On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. LDA must be at least max( 1, n ).
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 148 of file dsyr2.f.
Author
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