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HPL_dgemv(3)		      HPL Library Functions		    HPL_dgemv(3)

NAME
     HPL_dgemv - y := beta * y + alpha * op(A) * x.

SYNOPSIS
     #include "hpl.h"

     void  HPL_dgemv(  const  enum  HPL_ORDER ORDER, const enum HPL_TRANS TRANS,
     const int M, const int N, const double ALPHA, const double * A,  const  int
     LDA, const double * X, const int INCX, const double BETA, double * Y, const
     int INCY );

DESCRIPTION
     HPL_dgemv performs one of the matrix-vector operations

	 y := alpha * op( A ) * x + beta * y,

      where op( X ) is one of

	 op( X ) = X   or   op( X ) = X^T.

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

ARGUMENTS
     ORDER   (local input)	     const enum HPL_ORDER
	     On entry, ORDER  specifies the storage format of  the  operands  as
	     follows:
		ORDER = HplRowMajor,
		ORDER = HplColumnMajor.

     TRANS   (local input)	     const enum HPL_TRANS
	     On  entry,  TRANS	specifies the  operation to be performed as fol-
	     lows:
		TRANS = HplNoTrans y := alpha*A  *x + beta*y,
		TRANS = HplTrans   y := alpha*A^T*x + beta*y.

     M	     (local input)	     const int
	     On entry,	M  specifies  the number of rows of  the  matrix  A.   M
	     must be at least zero.

     N	     (local input)	     const int
	     On  entry,  N   specifies the number of columns of the matrix A.  N
	     must be at least zero.

     ALPHA   (local input)	     const double
	     On entry, ALPHA specifies the scalar alpha.   When  ALPHA	is  sup-
	     plied as zero then  A and X  need not be set on input.

     A	     (local input)	     const double *
	     On  entry,  A  points  to an array of size equal to or greater than
	     LDA * n.  Before  entry, the leading m by n part  of the  array   A
	     must contain the matrix coefficients.

     LDA     (local input)	     const int
	     On  entry,   LDA  specifies  the  leading	dimension  of  A  as de-
	     clared  in  the  calling  (sub) program.  LDA  must  be   at  least
	     MAX(1,m).

     X	     (local input)	     const double *
	     On entry,	X  is an incremented array of dimension  at  least ( 1 +
	     ( n - 1 ) * abs( INCX ) )	that  contains the vector x.

     INCX    (local input)	     const int
	     On entry, INCX specifies the increment for the elements of X.  INCX
	     must not be zero.

     BETA    (local input)	     const double
	     On  entry, BETA  specifies the scalar beta.    When  ALPHA  is sup-
	     plied as zero then  Y  need not be set on input.

     Y	     (local input/output)    double *
	     On entry,	Y  is an incremented array of dimension  at  least ( 1 +
	     ( n - 1 ) * abs( INCY ) )	that  contains the vector y.  Before en-
	     try with BETA non-zero, the incremented array Y  must  contain  the
	     vector  y.  On exit,  Y  is  overwritten  by  the updated vector y.

     INCY    (local input)	     const int
	     On entry, INCY specifies the increment for the elements of Y.  INCY
	     must not be zero.

EXAMPLE
     #include "hpl.h"

     int main(int argc, char *argv[])
     {
	double a[2*2], x[2], y[2];
	a[0] = 1.0; a[1] = 2.0; a[2] = 3.0; a[3] = 3.0;
	x[0] = 2.0; x[1] = 1.0; y[2] = 1.0; y[3] = 2.0;
	HPL_dgemv( HplColumnMajor, HplNoTrans, 2, 2, 2.0,
		   a, 2, x, 1, -1.0, y, 1 );
	printf("y=[%f,%f]\n", y[0], y[1]);
	exit(0); return(0);
     }

SEE ALSO
     HPL_dger (3), HPL_dtrsv (3).

HPL 2.3 			December 2, 2018		    HPL_dgemv(3)

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