code: public static void mult(int size, DoubleVector x, DoubleMatrix A, 
  		DoubleVector y, boolean isTransposed) {
  	// isTransposed = false:	x = A * y
  	// isTransposed = true:		x^t = y^t * A^t
  	
  	int i, j;
  	
  	if (!isTransposed) {
  	    // for beta
  	    // x = A * y
  	    for (i = 0; i < size; i++) {	
  		x.vect[i] = 0;
  		for (j = 0; j < size; j++) {
  		    x.vect[i] += A.mtrx[i][j] * y.vect[j];
  		}
  	    }
  	    
  	} else {
  	    // for alpha
  	    // x^t = y^t * A^t
  	    for (i = 0; i < size; i++) {
  		x.vect[i] = 0;
  		for (j = 0; j < size; j++) {
  		    x.vect[i] += y.vect[j] * A.mtrx[j][i];
  		}
  	    }	    
  	}	
      }
docs: Mult.
  
  @param size the size
  @param x the x
  @param A the a
  @param y the y
  @param isTransposed the is transposed