File: mvmpy.c

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python-scipy 0.14.0-2
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/*                                                     mvmpy.c
 *
 *     Matrix times vector
 *
 *
 *
 * SYNOPSIS:
 *
 * int r, c;
 * double A[r*c], V[c], Y[r];
 *
 * mvmpy( r, c, A, V, Y );
 *
 *
 *
 * DESCRIPTION:
 *
 *          c-1
 *          --
 * Y[j] =   >   A[j][k] V[k] ,  j = 1, ..., r
 *          --
 *          k=0
 *
 * Multiplies the r (rows) by c (columns) matrix A on the left
 * by column vector V of dimension c on the right
 * to produce a (column) vector Y output of dimension r.
 *
 *
 *
 *
 */


void mvmpy(r, c, A, V, Y)
int r, c;
double *A, *V, *Y;
{
    register double s;
    double *pA, *pV, *pY;
    int i, j;

    pA = A;
    pY = Y;
    for (i = 0; i < r; i++) {
	pV = V;
	s = 0.0;
	for (j = 0; j < c; j++) {
	    s += *pA++ * *pV++;
	}
	*pY++ = s;
    }
}