code: public Vec multiply(Vec b)
      {
          DenseVector result = new  DenseVector(rows());
          multiply(b, 1.0, result);
          return result;
      }
docs: Creates a new vector that is equal to <i>A*<b>b</b> </i>
  @param b the vector to multiply by
  @return a new vector <i>A*<b>b</b> </i>