Contents
sspr2 - perform the symmetric rank 2 operation A :=
alpha*x*y' + alpha*y*x' + A
SUBROUTINE SSPR2(UPLO, N, ALPHA, X, INCX, Y, INCY, AP)
CHARACTER * 1 UPLO
INTEGER N, INCX, INCY
REAL ALPHA
REAL X(*), Y(*), AP(*)
SUBROUTINE SSPR2_64(UPLO, N, ALPHA, X, INCX, Y, INCY, AP)
CHARACTER * 1 UPLO
INTEGER*8 N, INCX, INCY
REAL ALPHA
REAL X(*), Y(*), AP(*)
F95 INTERFACE
SUBROUTINE SPR2(UPLO, [N], ALPHA, X, [INCX], Y, [INCY], AP)
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, INCX, INCY
REAL :: ALPHA
REAL, 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 :: ALPHA
REAL, DIMENSION(:) :: X, Y, AP
C INTERFACE
#include <sunperf.h>
void sspr2(char uplo, int n, float alpha, float *x, int
incx, float *y, int incy, float *ap);
void sspr2_64(char uplo, long n, float alpha, float *x, long
incx, float *y, long incy, float *ap);
sspr2 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 A 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)
Real 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)
Real 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)
Real 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 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 A 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 sym-
metric matrix packed sequentially, 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 triangular part of the
updated matrix.