2 rational.cc -- implement Rational
4 source file of the Flower Library
6 (c) 1997--2000 Han-Wen Nienhuys <hanwen@cs.uu.nl>
10 #include "rational.hh"
12 #include "string-convert.hh"
13 #include "libc-extension.hh"
15 Rational::operator double () const
17 return (double)sign_ * num_ / den_;
22 operator << (ostream &o, Rational r)
31 Rational::trunc_rat () const
33 return Rational (num_ - (num_ % den_), den_);
42 Rational::Rational (int n, int d)
44 sign_ = ::sign (n) * ::sign (d);
50 Rational::Rational (int n)
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::div_rat (Rational div) const
94 return r.trunc_rat ();
98 Rational::mod_rat (Rational div) const
101 r = (r / div - r.div_rat (div)) * div;
106 Rational::normalise ()
125 int g = gcd (num_ , den_);
132 Rational::sign () const
134 return ::sign (sign_);
138 Rational::compare (Rational const &r, Rational const &s)
140 if (r.sign_ < s.sign_)
142 else if (r.sign_ > s.sign_)
144 else if (r.infty_b ())
146 else if (r.sign_ == 0)
150 return r.sign_ * ::sign (int (r.num_ * s.den_) - int (s.num_ * r.den_));
155 compare (Rational const &r, Rational const &s)
157 return Rational::compare (r, s );
161 Rational::operator %= (Rational r)
163 *this = r.mod_rat (r);
168 Rational::operator += (Rational r)
172 else if (r.infty_b ())
178 int n = sign_ * num_ *r.den_ + r.sign_ * den_ * r.num_;
179 int d = den_ * r.den_;
180 sign_ = ::sign (n) * ::sign (d);
190 copied from libg++ 2.8.0
192 Rational::Rational (double x)
200 double mantissa = frexp (x, &expt);
202 const int FACT = 1 << 20;
205 Thanks to Afie for this too simple idea.
207 do not blindly substitute by libg++ code, since that uses
208 arbitrary-size integers. The rationals would overflow too
212 num_ = (unsigned int) (mantissa * FACT);
213 den_ = (unsigned int) FACT;
240 Rational::operator *= (Rational r)
242 sign_ *= ::sign (r.sign_);
258 Rational::operator /= (Rational r)
271 Rational::operator -= (Rational r)
278 Rational::string () const
282 String s (sign_ > 0 ? "" : "-" );
283 return String (s + "infinity");
285 String s = to_string (num ());
286 if (den () != 1 && num ())
287 s += "/" + to_string (den ());
292 Rational::to_int () const
294 return num () / den ();