dsyr2(3P) Sun Performance Library dsyr2(3P)NAMEdsyr2 - perform the symmetric rank 2 operation A := alpha*x*y' +
alpha*y*x' + A
SYNOPSIS
SUBROUTINE DSYR2(UPLO, N, ALPHA, X, INCX, Y, INCY, A, LDA)
CHARACTER * 1 UPLO
INTEGER N, INCX, INCY, LDA
DOUBLE PRECISION ALPHA
DOUBLE PRECISION X(*), Y(*), A(LDA,*)
SUBROUTINE DSYR2_64(UPLO, N, ALPHA, X, INCX, Y, INCY, A, LDA)
CHARACTER * 1 UPLO
INTEGER*8 N, INCX, INCY, LDA
DOUBLE PRECISION ALPHA
DOUBLE PRECISION X(*), Y(*), A(LDA,*)
F95 INTERFACE
SUBROUTINE SYR2(UPLO, [N], ALPHA, X, [INCX], Y, [INCY], A, [LDA])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, INCX, INCY, LDA
REAL(8) :: ALPHA
REAL(8), DIMENSION(:) :: X, Y
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE SYR2_64(UPLO, [N], ALPHA, X, [INCX], Y, [INCY], A, [LDA])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, INCX, INCY, LDA
REAL(8) :: ALPHA
REAL(8), DIMENSION(:) :: X, Y
REAL(8), DIMENSION(:,:) :: A
C INTERFACE
#include <sunperf.h>
void dsyr2(char uplo, int n, double alpha, double *x, int incx, double
*y, int incy, double *a, int lda);
void dsyr2_64(char uplo, long n, double alpha, double *x, long incx,
double *y, long incy, double *a, long lda);
PURPOSEdsyr2 performs the symmetric rank 2 operation A := alpha*x*y' +
alpha*y*x' + A, where alpha is a scalar, x and y are n element vectors
and A is an n by n symmetric matrix.
ARGUMENTS
UPLO (input)
On entry, UPLO specifies whether the upper or lower triangu‐
lar 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.
Unchanged on exit.
N (input)
On entry, N specifies the order of the matrix A. N >= 0.
Unchanged on exit.
ALPHA (input)
On entry, ALPHA specifies the scalar alpha. Unchanged on
exit.
X (input)
( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented
array X must contain the n element vector x. Unchanged on
exit.
INCX (input)
On entry, INCX specifies the increment for the elements of X.
INCX <> 0. Unchanged on exit.
Y (input)
( 1 + ( n - 1 )*abs( INCY ) ). Before entry, the incremented
array Y must contain the n element vector y. Unchanged on
exit.
INCY (input)
On entry, INCY specifies the increment for the elements of Y.
INCY <> 0. Unchanged on exit.
A (input/output)
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 (input)
On entry, LDA specifies the first dimension of A as declared
in the calling (sub) program. LDA >= max( 1, n ). Unchanged
on exit.
6 Mar 2009 dsyr2(3P)
