Contents
ssyr2 - perform the symmetric rank 2 operation A :=
alpha*x*y' + alpha*y*x' + A
SUBROUTINE SSYR2(UPLO, N, ALPHA, X, INCX, Y, INCY, A, LDA)
CHARACTER * 1 UPLO
INTEGER N, INCX, INCY, LDA
REAL ALPHA
REAL X(*), Y(*), A(LDA,*)
SUBROUTINE SSYR2_64(UPLO, N, ALPHA, X, INCX, Y, INCY, A, LDA)
CHARACTER * 1 UPLO
INTEGER*8 N, INCX, INCY, LDA
REAL ALPHA
REAL 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 :: ALPHA
REAL, DIMENSION(:) :: X, Y
REAL, 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 :: ALPHA
REAL, DIMENSION(:) :: X, Y
REAL, DIMENSION(:,:) :: A
C INTERFACE
#include <sunperf.h>
void ssyr2(char uplo, int n, float alpha, float *x, int
incx, float *y, int incy, float *a, int lda);
void ssyr2_64(char uplo, long n, float alpha, float *x, long
incx, float *y, long incy, float *a, long lda);
ssyr2 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.
UPLO (input)
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.
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.