2 rational.cc -- implement Rational
4 source file of the Flower Library
6 (c) 1997--1999 Han-Wen Nienhuys <hanwen@cs.uu.nl>
11 #include "string-convert.hh"
12 #include "libc-extension.hh"
14 Rational::operator bool () const
19 Rational::operator int () const
21 return sign_ * num_ / den_;
24 Rational::operator double () const
26 return (double)sign_ * num_ / den_;
30 operator << (ostream &o, Rational r)
37 Rational::trunc_rat () const
39 return Rational(num_ - (num_ % den_), den_);
48 Rational::Rational (int n, int d)
50 sign_ = ::sign (n) * ::sign (d);
57 int gcd (int a, int b)
69 int lcm (int a, int b)
71 return abs (a*b / gcd (a,b));
75 Rational::set_infinite (int s)
77 sign_ = ::sign (s) * 2;
81 Rational::operator - () const
89 Rational::div_rat (Rational div) const
93 return r.trunc_rat ();
97 Rational::mod_rat (Rational div) const
100 r = (r / div - r.div_rat (div)) * div;
105 Rational::normalise ()
118 int g = gcd (num_ , den_);
125 Rational::sign () const
127 return ::sign (sign_);
131 Rational::infty_b () const
133 return abs (sign_) > 1;
137 Rational::compare (Rational const &r, Rational const &s)
139 if (r.sign_ < s.sign_)
141 else if (r.sign_ > s.sign_)
143 else if (r.infty_b ())
146 return (r - s).sign ();
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)
167 else if (r.infty_b ())
173 int n = sign_ * num_ *r.den_ + r.sign_ * den_ * r.num_;
174 int d = den_ * r.den_;
175 sign_ = ::sign (n) * ::sign(d);
185 copied from libg++ 2.8.0
187 Rational::Rational(double x)
195 double mantissa = frexp(x, &expt);
197 const int FACT = 1 << 20;
200 Thanks to Afie for this too simple idea.
202 do not blindly substitute by libg++ code, since that uses
203 arbitrary-size integers. The rationals would overflow too
207 num_ = (unsigned int) (mantissa * FACT);
208 den_ = (unsigned int) FACT;
235 Rational::operator *= (Rational r)
237 sign_ *= ::sign (r.sign_);
253 Rational::operator /= (Rational r)
266 Rational::operator -= (Rational r)
273 be paranoid about overiding libg++ stuff
276 Rational::operator = (Rational const &r)
283 Rational::str () const
287 String s (sign_ > 0 ? "" : "-" );
288 return String (s + "infinity");
290 String s = to_str (num ());
291 if (den () != 1 && num ())
292 s += "/" + to_str (den ());