dsyr2.f man page

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.

N

N is INTEGER
 On entry, N specifies the order of the matrix A.
 N must be at least zero.

ALPHA

ALPHA is DOUBLE PRECISION.
 On entry, ALPHA specifies the scalar alpha.

X

X 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.

INCX

INCX is INTEGER
 On entry, INCX specifies the increment for the elements of
 X. INCX must not be zero.

Y

Y 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.

INCY

INCY is INTEGER
 On entry, INCY specifies the increment for the elements of
 Y. INCY must not be zero.

A

A 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.

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 dsyr2.f.

Author

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Referenced By

dsyr2(3) is an alias of dsyr2.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK