code: public Matrix timesEquals(double s)
      {
          for (int i = 0; i < m; i++)
          {
              for (int j = 0; j < n; j++)
              {
                  A[i][j] = s * A[i][j];
              }
          }
          return this;
      }
docs: Multiply a matrix by a scalar in place, A = s*A
  
  @param s scalar
  @return replace A by s*A