chpr2
chpr2 - perform the Hermitian rank 2 operation A := alpha*x*conjg( y' ) + conjg( alpha )*y*conjg( x' ) + A
SUBROUTINE CHPR2( UPLO, N, ALPHA, X, INCX, Y, INCY, A)
CHARACTER * 1 UPLO
COMPLEX ALPHA
COMPLEX X(*), Y(*), A(*)
INTEGER N, INCX, INCY
SUBROUTINE CHPR2_64( UPLO, N, ALPHA, X, INCX, Y, INCY, A)
CHARACTER * 1 UPLO
COMPLEX ALPHA
COMPLEX X(*), Y(*), A(*)
INTEGER*8 N, INCX, INCY
SUBROUTINE HPR2( UPLO, [N], ALPHA, X, [INCX], Y, [INCY], A)
CHARACTER(LEN=1) :: UPLO
COMPLEX :: ALPHA
COMPLEX, DIMENSION(:) :: X, Y, A
INTEGER :: N, INCX, INCY
SUBROUTINE HPR2_64( UPLO, [N], ALPHA, X, [INCX], Y, [INCY], A)
CHARACTER(LEN=1) :: UPLO
COMPLEX :: ALPHA
COMPLEX, DIMENSION(:) :: X, Y, A
INTEGER(8) :: N, INCX, INCY
#include <sunperf.h>
void chpr2(char uplo, int n, complex alpha, complex *x, int incx, complex *y, int incy, complex *a);
void chpr2_64(char uplo, long n, complex alpha, complex *x, long incx, complex *y, long incy, complex *a);
chpr2 performs the Hermitian rank 2 operation
A := alpha*x*conjg( y' ) + conjg( alpha )*y*conjg( x' ) + A
where alpha is a scalar, x and y are n element vectors and A is an
n by n hermitian 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 A.
UPLO = 'L' or 'l' The lower triangular part of A is
supplied in A.
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)
-
( ( n*( n + 1 ) )/2 ).
Before entry with UPLO = 'U' or 'u', the array A must
contain the upper triangular part of the hermitian matrix
packed sequentially, column by column, so that A( 1 )
contains a( 1, 1 ), A( 2 ) and A( 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 A must
contain the lower triangular part of the hermitian matrix
packed sequentially, column by column, so that A( 1 )
contains a( 1, 1 ), A( 2 ) and A( 3 ) contain a( 2, 1 )
and a( 3, 1 ) respectively, and so on. On exit, the array
A is overwritten by the lower triangular part of the
updated matrix.
Note that the imaginary parts of the diagonal elements need
not be set, they are assumed to be zero, and on exit they
are set to zero.