.TH SSYR 1 "November 2006" "BLAS routine" "BLAS routine"
.SH NAME
SSYR - the symmetric rank 1 operation A := alpha*x*x\(aq + A,
.SH SYNOPSIS
.TP 43
SUBROUTINE SSYR(UPLO,N,ALPHA,X,INCX,A,LDA)
.TP 43
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REAL
ALPHA
.TP 43
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INTEGER
INCX,LDA,N
.TP 43
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CHARACTER
UPLO
.TP 43
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REAL
A(LDA,*),X(*)
.SH PURPOSE
SSYR performs the symmetric rank 1 operation
where alpha is a real scalar, x is an n element vector and A is an
n by n symmetric matrix.
.br
.SH ARGUMENTS
.TP 7
UPLO - CHARACTER*1.
On entry, UPLO specifies whether the upper or lower
triangular part of the array A is to be referenced as
follows:
UPLO = \(aqU\(aq or \(aqu\(aq Only the upper triangular part of A
is to be referenced.
UPLO = \(aqL\(aq or \(aql\(aq Only the lower triangular part of A
is to be referenced.
Unchanged on exit.
.TP 7
N - INTEGER.
On entry, N specifies the order of the matrix A.
N must be at least zero.
Unchanged on exit.
.TP 7
ALPHA - REAL .
On entry, ALPHA specifies the scalar alpha.
Unchanged on exit.
.TP 7
X - REAL array of dimension at least
( 1 + ( n - 1 )*abs( INCX ) ).
Before entry, the incremented array X must contain the n
element vector x.
Unchanged on exit.
.TP 7
INCX - INTEGER.
On entry, INCX specifies the increment for the elements of
X. INCX must not be zero.
Unchanged on exit.
.TP 7
A - REAL array of DIMENSION ( LDA, n ).
Before entry with UPLO = \(aqU\(aq or \(aqu\(aq, 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 = \(aqL\(aq or \(aql\(aq, 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.
.TP 7
LDA - 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 ).
Unchanged on exit.
Level 2 Blas routine.
-- 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.