SSYR2 (3) Linux Manual Page

ssyr2.f –

Synopsis

Functions/Subroutines

subroutine ssyr2 (UPLO, N, ALPHA, X, INCX, Y, INCY, A, LDA)
SSYR2

Function/Subroutine Documentation

subroutine ssyr2 (characterUPLO, integerN, realALPHA, real, dimension(*)X, integerINCX, real, dimension(*)Y, integerINCY, real, dimension(lda,*)A, integerLDA)

SSYR2 Purpose:

 SSYR2 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.

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.

X

 X 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.

INCX

 INCX is INTEGER

 On entry, INCX specifies the increment for the elements of

 X. INCX must not be zero.

Y

 Y 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.

INCY

 INCY is INTEGER

 On entry, INCY specifies the increment for the elements of

 Y. INCY must not be zero.

A

 A is REAL 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.

LDA

 LDA 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 22-October-1986.

 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 ssyr2.f.

Author

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