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HPL_dger(3)                  HPL Library Functions                 HPL_dger(3)


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 (3), HPL_dtrsv (3).

HPL 2.1                        October 26, 2012                    HPL_dger(3)

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