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NAME
     dgemv - perform one of the  matrix-vector  operations  y  :=
     alpha*A*x + beta*y or y := alpha*A'*x + beta*y

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

     DOUBLE PRECISION ALPHA, BETA

     INTEGER INCX, INCY, LDA, M, N

     CHARACTER*1 TRANS

     DOUBLE PRECISION A( LDA, * ), X( * ), Y( * )



     #include <sunperf.h>

     void dgemv(char trans, int m, int n,  double  alpha,  double
               *da,  int lda, double *dx, int incx, double dbeta,
               double *dy, int incy) ;

PURPOSE
     DGEMV  performs one of the  matrix-vector  operations  y  :=
     alpha*A*x  +  beta*y or y := alpha*A'*x + beta*y 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*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     - DOUBLE PRECISION.
               On  entry,  ALPHA  specifies  the  scalar   alpha.
               Unchanged on exit.

     A         - DOUBLE PRECISION 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         - DOUBLE PRECISION 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
               elements  of  X. INCX must not be zero.  Unchanged
               on exit.

     BETA      - DOUBLE PRECISION.
               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         - DOUBLE PRECISION 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
               elements  of  Y. INCY must not be zero.  Unchanged
               on exit.

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