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zgemv

```
NAME
ZGEMV - perform one of the matrix-vector operations   y :=
alpha*A*x + beta*y, or y := alpha*A'*x + beta*y, or   y :=
alpha*conjg( A' )*x + beta*y,

SYNOPSIS
SUBROUTINE ZGEMV ( TRANS, M, N, ALPHA, A, LDA, X, INCX,
BETA, Y, INCY )

COMPLEX*16   ALPHA, BETA

INTEGER      INCX, INCY, LDA, M, N

CHARACTER*1  TRANS

COMPLEX*16   A( LDA, * ), X( * ), Y( * )

PURPOSE
ZGEMV  performs one of the matrix-vector operations

where alpha and beta are scalars, x and y are vectors and A
is an m by n matrix.

PARAMETERS
TRANS  - CHARACTER*1.
On entry, TRANS specifies the operation to be per-
formed as follows:

TRANS = 'N' or 'n'   y := alpha*A*x + beta*y.

TRANS = 'T' or 't'   y := alpha*A'*x + beta*y.

TRANS = 'C' or 'c'   y := alpha*conjg( A' )*x +
beta*y.

Unchanged on exit.

M      - INTEGER.
On entry, M specifies the number of rows of the
matrix A.  M must be at least zero.  Unchanged on
exit.

N      - INTEGER.
On entry, N specifies the number of columns of the
matrix A.  N must be at least zero.  Unchanged on
exit.

ALPHA  - COMPLEX*16      .
On entry, ALPHA specifies the scalar alpha.
Unchanged on exit.

A      - COMPLEX*16       array of DIMENSION ( LDA, n ).
Before entry, the leading m by n part of the array A
must contain the matrix of coefficients.  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, m ).  Unchanged on exit.

X      - COMPLEX*16       array of DIMENSION at least
( 1 + ( n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n'
and at least ( 1 + ( m - 1 )*abs( INCX ) ) otherwise.
Before entry, the incremented array X must contain
the vector x.  Unchanged on exit.

INCX   - INTEGER.
On entry, INCX specifies the increment for the ele-
ments of X. INCX must not be zero.  Unchanged on
exit.

BETA   - COMPLEX*16      .
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*16       array of DIMENSION at least
( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N' or 'n'
and at least ( 1 + ( n - 1 )*abs( INCY ) ) otherwise.
Before entry with BETA non-zero, the incremented
array Y must contain the vector y. On exit, Y is
overwritten by the updated vector y.

INCY   - INTEGER.
On entry, INCY specifies the increment for the ele-
ments 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.
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