code: public static void fillRow(Matrix A, int i, int from, int to, double val)
      {
          for(int j = from; j < to; j++)
              A.set(i, j, val);
      }
docs: Fills the values in a row of the matrix
  @param A the matrix in question
  @param i the row of the matrix
  @param from the first column index to fill (inclusive)
  @param to the last column index to fill (exclusive)
  @param val the value to fill into the matrix