NAME¶
CHEMV - perform the matrix-vector operation y := alpha*A*x + beta*y,
SYNOPSIS¶
- SUBROUTINE CHEMV
- ( UPLO, N, ALPHA, A, LDA, X, INCX, BETA, Y, INCY )
COMPLEX ALPHA, BETA INTEGER INCX, INCY, LDA, N CHARACTER*1 UPLO COMPLEX A( LDA,
* ), X( * ), Y( * )
PURPOSE¶
CHEMV performs the matrix-vector operation
where alpha and beta are scalars, x and y are n element vectors and A is an n by
n hermitian matrix.
PARAMETERS¶
- 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 = '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 - 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.
- A - COMPLEX array of DIMENSION ( LDA, n ).
- 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
hermitian matrix and the strictly lower triangular part of A is not
referenced. 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 hermitian matrix and the strictly upper triangular part of A is not
referenced. Note that the imaginary parts of the diagonal elements need
not be set and are assumed to be zero. Unchanged on exit.
- 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.
- 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.
- BETA - COMPLEX .
- On entry, BETA specifies the scalar beta. When BETA is supplied as zero
then Y need not be set on input. 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. On exit, Y is overwritten by the updated
vector y.
- INCY - INTEGER.
- On entry, INCY specifies the increment for the elements of Y. INCY must
not be zero. Unchanged on exit.
Level 2 Blas routine.
-- Written on 22-October-1986. Jack Dongarra, Argonne National Lab. Jeremy
Du Croz, Nag Central Office. Sven Hammarling, Nag Central Office. Richard
Hanson, Sandia National Labs.