HPL_dger HPL 2.2 Library Functions February 24, 2016

Name

HPL_dger A := alpha * x * y^T + A.

Synopsis

#include "hpl.h"

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

Description

HPL_dger performs the rank 1 operation A := alpha * x * y^T + A, where alpha is a scalar, x is an m-element vector, y is an n-element vector 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.                                   
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
        supplied as zero then  X and Y  need not be set on input.
X       (local input)                 const double *
        On entry,  X  is an incremented array of dimension  at  least
        ( 1 + ( m - 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.
Y       (local input)                 double *
        On entry,  Y  is an incremented array of dimension  at  least
        ( 1 + ( n - 1 ) * abs( INCY ) )  that  contains the vector y.
INCY    (local input)                 const int
        On entry, INCY specifies the increment for the elements of Y.
        INCY must not be zero.
A       (local input/output)          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. On exit, A is
        overwritten by the updated matrix.
LDA     (local input)                 const int
        On entry,  LDA  specifies  the  leading  dimension  of  A  as
        declared  in  the  calling  (sub) program.  LDA  must  be  at
        least MAX(1,m).

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_dger( HplColumnMajor, 2, 2, 2.0, x, 1, y, 1,
             a, 2 );
   printf("y=[%f,%f]\n", y[0], y[1]);
   exit(0); return(0);
}

See Also

HPL_dgemv, HPL_dtrsv.