2 rational.cc -- implement Rational
4 source file of the Flower Library
6 (c) 1997--2005 Han-Wen Nienhuys <hanwen@cs.uu.nl>
14 #include "string-convert.hh"
15 #include "libc-extension.hh"
17 Rational::operator double () const
19 return (double)sign_ * num_ / den_;
24 operator<< (ostream &o, Rational r)
32 Rational::trunc_rat () const
34 return Rational (num_ - (num_ % den_), den_);
43 Rational::Rational (int n, int d)
45 sign_ = ::sign (n) * ::sign (d);
51 Rational::Rational (int n)
59 int gcd (int a, int b)
71 Rational::set_infinite (int s)
73 sign_ = ::sign (s) * 2;
77 Rational::operator- () const
85 Rational::div_rat (Rational div) const
89 return r.trunc_rat ();
93 Rational::mod_rat (Rational div) const
96 r = (r / div - r.div_rat (div)) * div;
101 Rational::normalise ()
120 int g = gcd (num_, den_);
127 Rational::sign () const
129 return ::sign (sign_);
133 Rational::compare (Rational const &r, Rational const &s)
135 if (r.sign_ < s.sign_)
137 else if (r.sign_ > s.sign_)
139 else if (r.is_infinity ())
141 else if (r.sign_ == 0)
145 return r.sign_ * ::sign (int (r.num_ * s.den_) - int (s.num_ * r.den_));
150 compare (Rational const &r, Rational const &s)
152 return Rational::compare (r, s);
156 Rational::operator%= (Rational r)
158 *this = r.mod_rat (r);
163 Rational::operator+= (Rational r)
166 else if (r.is_infinity ())
172 int n = sign_ * num_ *r.den_ + r.sign_ * den_ * r.num_;
173 int d = den_ * r.den_;
174 sign_ = ::sign (n) * ::sign (d);
183 copied from libg++ 2.8.0
185 Rational::Rational (double x)
193 double mantissa = frexp (x, &expt);
195 const int FACT = 1 << 20;
198 Thanks to Afie for this too simple idea.
200 do not blindly substitute by libg++ code, since that uses
201 arbitrary-size integers. The rationals would overflow too
205 num_ = (unsigned int) (mantissa * FACT);
206 den_ = (unsigned int) FACT;
232 Rational::operator*= (Rational r)
234 sign_ *= ::sign (r.sign_);
235 if (r.is_infinity ())
250 Rational::operator/= (Rational r)
263 Rational::operator-= (Rational r)
270 Rational::to_string () const
274 String s (sign_ > 0 ? "" : "-");
275 return String (s + "infinity");
278 String s = ::to_string (num ());
279 if (den () != 1 && num ())
280 s += "/" + ::to_string (den ());
285 Rational::to_int () const
287 return num () / den ();
297 Rational::is_infinity () const
299 return sign_ == 2 || sign_ == -2;