2 rational.cc -- implement Rational
4 source file of the Flower Library
6 (c) 1997--1998 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::truncated () const
39 return Rational(num_ - (num_ % den_), den_);
48 Rational::Rational (int n, int d)
50 sign_ = ::sign (n) * ::sign (d);
58 int gcd (int a, int b)
70 int lcm (int a, int b)
72 return abs (a*b / gcd (a,b));
76 Rational::set_infinite (int s)
78 sign_ = ::sign (s) * 2;
82 Rational::operator - () const
90 Rational::normalise ()
103 int g = gcd (num_ , den_);
110 Rational::sign () const
112 return ::sign (sign_);
116 Rational::infty_b () const
118 return abs (sign_) > 1;
122 Rational::compare (Rational const &r, Rational const &s)
124 if (r.sign_ < s.sign_)
126 else if (r.sign_ > s.sign_)
128 else if (r.infty_b ())
131 return (r - s).sign ();
135 compare (Rational const &r, Rational const &s)
137 return Rational::compare (r, s );
141 Rational::operator += (Rational r)
145 else if (r.infty_b ())
151 int n = sign_ * num_ *r.den_ + r.sign_ * den_ * r.num_;
152 int d = den_ * r.den_;
153 sign_ = ::sign (n) * ::sign(d);
163 copied from libg++ 2.8.0
165 Rational::Rational(double x)
173 double mantissa = frexp(x, &expt);
175 const int FACT = 1 << 20;
182 suck me gently with a vacuum cleaner. Thanks to Afie for this wierd idea.
184 num_ = (unsigned int) (mantissa * FACT);
185 den_ = (unsigned int) FACT;
208 Rational::operator *= (Rational r)
210 sign_ *= ::sign (r.sign_);
226 Rational::operator /= (Rational r)
239 Rational::operator -= (Rational r)
246 be paranoid about overiding libg++ stuff
249 Rational::operator = (Rational const &r)
255 Rational::Rational (Rational const &r)
261 Rational::str () const
265 String s (sign_ > 0 ? "" : "-" );
266 return String (s + "infinity");
268 String s = to_str (num ());
269 if (den () != 1 && num ())
270 s += "/" + to_str (den ());