dspr2(3P) Sun Performance Library dspr2(3P)NAMEdspr2 - perform the symmetric rank 2 operation A := alpha*x*y' +
alpha*y*x' + A
SYNOPSIS
SUBROUTINE DSPR2(UPLO, N, ALPHA, X, INCX, Y, INCY, AP)
CHARACTER * 1 UPLO
INTEGER N, INCX, INCY
DOUBLE PRECISION ALPHA
DOUBLE PRECISION X(*), Y(*), AP(*)
SUBROUTINE DSPR2_64(UPLO, N, ALPHA, X, INCX, Y, INCY, AP)
CHARACTER * 1 UPLO
INTEGER*8 N, INCX, INCY
DOUBLE PRECISION ALPHA
DOUBLE PRECISION X(*), Y(*), AP(*)
F95 INTERFACE
SUBROUTINE SPR2(UPLO, [N], ALPHA, X, [INCX], Y, [INCY], AP)
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, INCX, INCY
REAL(8) :: ALPHA
REAL(8), DIMENSION(:) :: X, Y, AP
SUBROUTINE SPR2_64(UPLO, [N], ALPHA, X, [INCX], Y, [INCY], AP)
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, INCX, INCY
REAL(8) :: ALPHA
REAL(8), DIMENSION(:) :: X, Y, AP
C INTERFACE
#include <sunperf.h>
void dspr2(char uplo, int n, double alpha, double *x, int incx, double
*y, int incy, double *ap);
void dspr2_64(char uplo, long n, double alpha, double *x, long incx,
double *y, long incy, double *ap);
PURPOSEdspr2 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, supplied in packed form.
ARGUMENTS
UPLO (input)
On entry, UPLO specifies whether the upper or lower triangu‐
lar part of the matrix A is supplied in the packed array AP
as follows:
UPLO = 'U' or 'u' The upper triangular part of A is sup‐
plied in AP.
UPLO = 'L' or 'l' The lower triangular part of A is sup‐
plied in AP.
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)
Double precision array, dimension (1 + (n - 1)*abs(INCX))
Before entry, the incremented array X must contain the n ele‐
ment 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)
Double precision array, dimension (1 + (n - 1)*abs(INCY))
Before entry, the incremented array Y must contain the n ele‐
ment vector y. Unchanged on exit.
INCY (input)
On entry, INCY specifies the increment for the elements of Y.
INCY <> 0. Unchanged on exit.
AP (input/output)
Double precision array, dimension (( n*(n + 1))/2) Before
entry with UPLO = 'U' or 'u', the array AP must contain the
upper triangular part of the symmetric matrix packed sequen‐
tially, column by column, so that AP( 1 ) contains a( 1, 1 ),
AP( 2 ) and AP( 3 ) contain a( 1, 2 ) and a( 2, 2 ) respec‐
tively, and so on. On exit, the array AP is overwritten by
the upper triangular part of the updated matrix. Before
entry with UPLO = 'L' or 'l', the array AP must contain the
lower triangular part of the symmetric matrix packed sequen‐
tially, column by column, so that AP( 1 ) contains a( 1, 1 ),
AP( 2 ) and AP( 3 ) contain a( 2, 1 ) and a( 3, 1 ) respec‐
tively, and so on. On exit, the array AP is overwritten by
the lower triangular part of the updated matrix.
6 Mar 2009 dspr2(3P)
