cher2 (l)  Linux Man Pages
cher2: performs the hermitian rank 2 operation A := alpha*x*conjg( yaq ) + conjg( alpha )*y*conjg( xaq ) + A,
NAME
CHER2  performs the hermitian rank 2 operation A := alpha*x*conjg( yaq ) + conjg( alpha )*y*conjg( xaq ) + A,SYNOPSIS
 SUBROUTINE CHER2(UPLO,N,ALPHA,X,INCX,Y,INCY,A,LDA)
 COMPLEX ALPHA
 INTEGER INCX,INCY,LDA,N
 CHARACTER UPLO
 COMPLEX A(LDA,*),X(*),Y(*)
PURPOSE
CHER2 performs the hermitian rank 2 operation
where alpha is a scalar, x and y are n element vectors and A is an n
by n hermitian matrix.
ARGUMENTS
 UPLO  CHARACTER*1.

On entry, UPLO specifies whether the upper or lower
triangular part of the array A is to be referenced as
follows:
UPLO = aqUaq or aquaq Only the upper triangular part of A is to be referenced.
UPLO = aqLaq or aqlaq Only the lower triangular part of A is to be referenced.
Unchanged on exit.
 N  INTEGER.
 On entry, N specifies the order of the matrix A. N must be at least zero. Unchanged on exit.
 ALPHA  COMPLEX .
 On entry, ALPHA specifies the scalar alpha. Unchanged on exit.
 X  COMPLEX array of dimension at least
 ( 1 + ( n  1 )*abs( INCX ) ). Before entry, the incremented array X must contain the n element vector x. Unchanged on exit.
 INCX  INTEGER.
 On entry, INCX specifies the increment for the elements of X. INCX must not be zero. Unchanged on exit.
 Y  COMPLEX array of dimension at least
 ( 1 + ( n  1 )*abs( INCY ) ). Before entry, the incremented array Y must contain the n element vector y. Unchanged on exit.
 INCY  INTEGER.
 On entry, INCY specifies the increment for the elements of Y. INCY must not be zero. Unchanged on exit.
 A  COMPLEX array of DIMENSION ( LDA, n ).
 Before entry with UPLO = aqUaq or aquaq, the leading n by n upper triangular part of the array A must contain the upper triangular part of the hermitian 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 = aqLaq or aqlaq, the leading n by n lower triangular part of the array A must contain the lower triangular part of the hermitian 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. 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.
 LDA  INTEGER.
 On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. LDA must be at least max( 1, n ). Unchanged on exit.
FURTHER DETAILS
Level 2 Blas routine.
 Written on 22October1986.
Jack Dongarra, Argonne National Lab.
Jeremy Du Croz, Nag Central Office.
Sven Hammarling, Nag Central Office.
Richard Hanson, Sandia National Labs.