release: 1.5.10

[lilypond.git] / flower / rational.cc

diff --git a/flower/rational.cc b/flower/rational.cc
index 5b36be916cbbb29e617ec28424fccf6b2d60e4c4..3b0b3d0928da37a1a87c9b2b1f11245d3d5505f4 100644 (file)
--- a/flower/rational.cc
+++ b/flower/rational.cc
@@ -1,18 +1,307 @@
 /*
-  rational.cc -- implement Rational related functions
-
+  rational.cc -- implement Rational
+  
   source file of the Flower Library
 
-  (c) 1997 Han-Wen Nienhuys <hanwen@stack.nl>
+  (c)  1997--2000 Han-Wen Nienhuys <hanwen@cs.uu.nl>
 */
-
+#include <math.h>
+#include <stdlib.h>
 #include "rational.hh"
 #include "string.hh"
+#include "string-convert.hh"  
+#include "libc-extension.hh"
+
+Rational::operator double () const
+{
+  return (double)sign_ * num_ / den_;
+}
+
+ostream &
+operator << (ostream &o, Rational r)
+{
+  o <<  r.str ();
+  return o;
+}
+
+Rational
+Rational::trunc_rat () const
+{
+  return Rational (num_ - (num_ % den_), den_);
+}
+
+Rational::Rational ()
+{
+  sign_ = 0;
+  num_ = den_ = 1;
+}
+
+Rational::Rational (int n, int d)
+{
+  sign_ = ::sign (n) * ::sign (d);
+  num_ = abs (n);
+  den_ = abs (d);
+  normalise ();
+}
+
+Rational::Rational (int n)
+{
+  sign_ = ::sign (n);
+  num_ = abs (n);
+  den_= 1;
+}
+
+static
+int gcd (int a, int b)
+{
+  int t;
+  while ((t = a % b))
+    {
+      a = b;
+      b = t;
+    }
+  return b;
+}
+
+static
+int lcm (int a, int b)
+{
+  return abs (a*b / gcd (a,b));
+}
 
 void
-print_rat (Rational const &m)
+Rational::set_infinite (int s)
+{
+  sign_ = ::sign (s) * 2; 
+}
+
+Rational
+Rational::operator - () const
+{
+  Rational r (*this);
+  r.negate ();
+  return r;
+}
+
+Rational
+Rational::div_rat (Rational div) const
+{
+  Rational r (*this);
+  r /= div;
+  return r.trunc_rat ();
+}
+
+Rational
+Rational::mod_rat (Rational div) const
 {
-    cout << String (m) << flush;
+  Rational r (*this);
+  r = (r / div - r.div_rat (div)) * div;
+  return r;
+}
+
+void
+Rational::normalise ()
+{
+  if (!sign_)
+    {
+      den_ = 1;
+      num_ = 0;
+    }
+  else if (!den_)
+    {
+      sign_ = 2;
+      num_ = 1;
+    }
+  else if (!num_)
+    {
+      sign_ = 0;
+      den_ = 1;
+    }
+  else
+    {
+      int g = gcd (num_ , den_);
+
+      num_ /= g;
+      den_ /= g;
+    }
+}
+int
+Rational::sign () const
+{
+  return ::sign (sign_);
+}
+
+int
+Rational::compare (Rational const &r, Rational const &s)
+{
+  if (r.sign_ < s.sign_)
+    return -1;
+  else if (r.sign_ > s.sign_)
+    return 1;
+  else if (r.infty_b ())
+    return 0;
+  else if (r.sign_ == 0)
+    return 0;
+  else
+    {
+      /*
+       TODO: fix this code; (r-s).sign() is too expensive.
+       
+       return r.sign_ * ::sign  (r.num_ * s.den_ - s.num_ * r.den_);
+      */
+      return (r - s).sign ();
+    }
+}
+
+int
+compare (Rational const &r, Rational const &s)
+{
+  return Rational::compare (r, s );
+}
+
+Rational &
+Rational::operator %= (Rational r)
+{
+  *this = r.mod_rat (r);
+  return *this;
+}
+
+Rational &
+Rational::operator += (Rational r)
+{
+  if (infty_b ())
+    ;
+  else if (r.infty_b ())
+    {
+      *this = r;
+    }
+  else 
+    {
+      int n = sign_ * num_ *r.den_ + r.sign_ * den_ * r.num_;
+      int d = den_ * r.den_;
+      sign_ =  ::sign (n) * ::sign (d);
+      num_ = abs (n);
+      den_ = abs (d);
+      normalise ();
+    }
+  return *this;
 }
     
 
+/*
+  copied from libg++ 2.8.0
+ */ 
+Rational::Rational (double x)
+{
+  if (x != 0.0)
+    {
+      sign_ = ::sign (x);
+      x *= sign_;
+
+      int expt;
+      double mantissa = frexp (x, &expt);
+
+      const int FACT = 1 << 20;
+
+      /*
+       Thanks to Afie for this too simple  idea.
+
+       do not blindly substitute by libg++ code, since that uses
+       arbitrary-size integers.  The rationals would overflow too
+       easily.
+      */
+
+      num_ = (unsigned int) (mantissa * FACT);
+      den_ = (unsigned int) FACT;
+      normalise ();      
+      if (expt < 0)
+       den_ <<= -expt;
+      else
+       num_ <<= expt;
+      normalise ();
+    }
+  else
+    {
+      num_ = 0;
+      den_ = 1;
+      sign_ =0;
+      normalise ();
+    }
+}
+
+
+void
+Rational::invert ()
+{
+  int r (num_);
+  num_  = den_;
+  den_ = r;
+}
+
+Rational &
+Rational::operator *= (Rational r)
+{
+  sign_ *= ::sign (r.sign_);
+  if (r.infty_b ())
+    {  
+      sign_ = sign () * 2;
+      goto exit_func;
+    }
+
+  num_ *= r.num_;
+  den_ *= r.den_;
+
+  normalise ();
+ exit_func:
+  return *this;
+}
+  
+Rational &
+Rational::operator /= (Rational r)
+{
+  r.invert ();
+  return (*this *= r);
+}
+
+void
+Rational::negate ()
+{
+  sign_ *= -1;
+}
+
+Rational&
+Rational::operator -= (Rational r)
+{
+  r.negate ();
+  return (*this += r);
+}
+
+/*
+  be paranoid about overiding libg++ stuff
+ */
+Rational &
+Rational::operator = (Rational const &r)
+{
+  copy (r);
+  return *this;
+}
+
+String
+Rational::str () const
+{
+  if (infty_b ())
+    {
+      String s (sign_ > 0 ? "" : "-" );
+      return String (s + "infinity");
+    }
+  String s = to_str (num ());
+  if (den () != 1 && num ())
+    s += "/" + to_str (den ());
+  return s;
+}
+
+int
+sign (Rational r)
+{
+  return r.sign ();
+}