#define X(i,j) x[i][j]
#define Y(i,j) y[i][j]
#define Z(i,j) z[i][j]

void matmul( x, y, z, m, n, p)	/* x = y * z */
double *x[];
double *y[];
double *z[];
int m, n, p;
{
    int i, j, k;

    for( i = 0; i < m; i++)
	for( j = 0; j < p; j++) {
	    X(i,j) = 0;
	    for( k = 0; k < n; k++)
		X(i,j) += Y(i,k) * Z(k,j);
	}
}