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_;
21 operator << (ostream &o, Rational r)
28 Rational::trunc_rat () const
30 return Rational (num_ - (num_ % den_), den_);
39 Rational::Rational (int n, int d)
41 sign_ = ::sign (n) * ::sign (d);
48 int gcd (int a, int b)
60 int lcm (int a, int b)
62 return abs (a*b / gcd (a,b));
66 Rational::set_infinite (int s)
68 sign_ = ::sign (s) * 2;
72 Rational::operator - () const
80 Rational::div_rat (Rational div) const
84 return r.trunc_rat ();
88 Rational::mod_rat (Rational div) const
91 r = (r / div - r.div_rat (div)) * div;
96 Rational::normalise ()
109 int g = gcd (num_ , den_);
116 Rational::sign () const
118 return ::sign (sign_);
122 Rational::infty_b () const
124 return abs (sign_) > 1;
128 Rational::compare (Rational const &r, Rational const &s)
130 if (r.sign_ < s.sign_)
132 else if (r.sign_ > s.sign_)
134 else if (r.infty_b ())
137 return (r - s).sign ();
141 compare (Rational const &r, Rational const &s)
143 return Rational::compare (r, s );
147 Rational::operator %= (Rational r)
149 *this = r.mod_rat (r);
154 Rational::operator += (Rational r)
158 else if (r.infty_b ())
164 int n = sign_ * num_ *r.den_ + r.sign_ * den_ * r.num_;
165 int d = den_ * r.den_;
166 sign_ = ::sign (n) * ::sign (d);
176 copied from libg++ 2.8.0
178 Rational::Rational (double x)
186 double mantissa = frexp (x, &expt);
188 const int FACT = 1 << 20;
191 Thanks to Afie for this too simple idea.
193 do not blindly substitute by libg++ code, since that uses
194 arbitrary-size integers. The rationals would overflow too
198 num_ = (unsigned int) (mantissa * FACT);
199 den_ = (unsigned int) FACT;
226 Rational::operator *= (Rational r)
228 sign_ *= ::sign (r.sign_);
244 Rational::operator /= (Rational r)
257 Rational::operator -= (Rational r)
264 be paranoid about overiding libg++ stuff
267 Rational::operator = (Rational const &r)
274 Rational::str () const
278 String s (sign_ > 0 ? "" : "-" );
279 return String (s + "infinity");
281 String s = to_str (num ());
282 if (den () != 1 && num ())
283 s += "/" + to_str (den ());