Contents
dspr2 - perform the symmetric rank 2 operation A :=
alpha*x*y' + alpha*y*x' + A
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);
dspr2 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.
UPLO (input)
On entry, UPLO specifies whether the upper or
lower triangular 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 supplied in AP.
UPLO = 'L' or 'l' The lower triangular part of A
is supplied 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 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)
Double precision array, dimension (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.
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 sym-
metric matrix packed sequentially, column by
column, so that AP( 1 ) contains a( 1, 1 ), AP( 2
) and AP( 3 ) contain a( 1, 2 ) and a( 2, 2 )
respectively, 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 triangu-
lar 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 ) respectively, and so on. On exit,
the array AP is overwritten by the lower triangu-
lar part of the updated matrix.