release: 0.1.53

[lilypond.git] / flower / rational.cc

diff --git a/flower/rational.cc b/flower/rational.cc
index 5b36be916cbbb29e617ec28424fccf6b2d60e4c4..df18b4cbcd57cf5b0ecd2d8368d36d667e576698 100644 (file)
--- a/flower/rational.cc
+++ b/flower/rational.cc
@@ -1,18 +1,288 @@
 /*
-  rational.cc -- implement Rational related functions
-
+  rational.cc -- implement Rational
+  
   source file of the Flower Library
 
   (c) 1997 Han-Wen Nienhuys <hanwen@stack.nl>
 */
-
+#include <stdlib.h>
 #include "rational.hh"
 #include "string.hh"
+#include "string-convert.hh"  
+#include "libc-extension.hh"
+
+Rational::operator bool () const
+{
+  return sign_;
+}
+
+Rational::operator int () const
+{
+  return sign_ * num_ / den_;
+}
+
+Rational::operator double () const
+{
+  return (double)sign_ * num_ / den_;
+}
+
+ostream &
+operator << (ostream &o, Rational r)
+{
+  o <<  r.str ();
+  return o;
+}
+
+
+
+Rational
+Rational::truncated () const
+{
+  return Rational(num_ - (num_ % den_), den_);
+}
+
+Rational::Rational ()
+{
+  sign_ = 1;
+  num_ = den_ = 1;
+}
+
+Rational::Rational (int n, int d)
+{
+  sign_ = ::sign (n) * ::sign (d);
+  num_ = abs (n);
+  den_ = abs (d);
+  normalise ();
+}
+
+
+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
+Rational::set_infinite (int s)
+{
+  sign_ = ::sign (s) * 2; 
+}
+
+Rational
+Rational::operator - () const
+{
+  Rational r(*this);
+  r.negate ();
+  return r;
+}
 
 void
-print_rat (Rational const &m)
+Rational::normalise ()
+{
+  if (!sign_)
+    {
+      den_ = 1;
+      num_ = 0;
+      return ;
+    }
+  if (!den_)
+    sign_ = 2;
+  if (!num_)
+    sign_ = 0;
+
+  int g = gcd (num_ , den_);
+
+  num_ /= g;
+  den_ /= g;
+}
+
+int
+Rational::sign () const
+{
+  return ::sign (sign_);
+}
+
+bool
+Rational::infty_b () const
+{
+  return abs (sign_) > 1;
+}
+
+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;
+
+  return  (r - s).sign ();
+}
+
+int
+compare (Rational const &r, Rational const &s)
 {
-    cout << String (m) << flush;
+  return Rational::compare (r, s );
+}
+
+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)
+{
+  num_ = 0;
+  den_ = 1;
+  if (x != 0.0)
+    {
+      sign_ = ::sign (x);
+      x *= sign_;
+
+      const long shift = 15;         // a safe shift per step
+      const double width = 32768.0;  // = 2^shift
+      const int maxiter = 20;        // ought not be necessary, but just in case,
+      // max 300 bits of precision
+      int expt;
+      double mantissa = frexp(x, &expt);
+      long exponent = expt;
+      double intpart;
+      int k = 0;
+      while (mantissa != 0.0 && k++ < maxiter)
+       {
+         mantissa *= width;
+         mantissa = modf(mantissa, &intpart);
+         num_ <<= shift;
+         num_ += (long)intpart;
+         exponent -= shift;
+       }
+      if (exponent > 0)
+       num_ <<= exponent;
+      else if (exponent < 0)
+       den_ <<= -exponent;
+    } else {
+      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;
+}
+
+Rational::Rational (Rational const &r)
+{
+  copy (r);
+}
+
+Rational::operator String () const
+{
+  return str ();
+}
+
+String
+Rational::str () const
+{
+  if (infty_b ())
+    {
+      String s (sign_ > 0 ? "" : "-" );
+      return String (s + "infinity");
+    }
+  String s (num ());
+  if (den () != 1 && num ())
+    s += "/" + String (den ());
+  return s;
+}
+
+int
+sign (Rational r)
+{
+  return r.sign ();
+}