code: public static void addRow(Matrix A, int i, int start, int to, double c)
      {
          for(int j = start; j < to; j++)
              A.increment(i, j, c);
      }
docs: Updates the values of row <tt>i</tt> in the given matrix to be A[i,:] = A[i,:]+ c
  
  @param A the matrix to perform he update on
  @param i the row to update
  @param start the first index of the row to update from (inclusive)
  @param to the last index of the row to update (exclusive)
  @param c the constant to add to each element