def __sub__(self, entry):
number_points = self.number_points - entry.number_points;<EOL>result_linear_sum = list_math_subtraction(self.linear_sum, entry.linear_sum);<EOL>result_square_sum = self.square_sum - entry.square_sum;<EOL>if ( (number_points < <NUM_LIT:0>) or (result_square_sum < <NUM_LIT:0>) ):<EOL><INDENT>raise NameError("<STR_LIT>");<EOL><DEDENT>return cfentry(number_points, result_linear_sum, result_square_sum)<EOL>
!
        @brief Overloaded operator sub. Performs substraction of two clustering features.
        @details Substraction can't be performed with clustering feature whose description is less then substractor.

        @param[in] entry (cfentry): Entry that is substracted from the current.

        @return (cfentry) Result of substraction of two clustering features.