Method IsNegative

extra/yassl/taocrypt/include/integer.hpp:183–183

        bool IsZero()      const { return !*this; }
        bool NotZero()     const { return !IsZero(); }
        bool IsNegative()  const { return sign_ == NEGATIVE; }
        bool NotNegative() const { return !IsNegative(); }
        bool IsPositive()  const { return NotNegative() && NotZero(); }
        bool NotPositive() const { return !IsPositive(); }