release: 1.1.24

[lilypond.git] / flower / rational.cc

diff --git a/flower/rational.cc b/flower/rational.cc
index df18b4cbcd57cf5b0ecd2d8368d36d667e576698..e99402dbb8a687503f184c1a2d112dc7a0bf8d59 100644 (file)
--- a/flower/rational.cc
+++ b/flower/rational.cc
@@ -3,7 +3,7 @@
   
   source file of the Flower Library
 
-  (c) 1997 Han-Wen Nienhuys <hanwen@stack.nl>
+  (c)  1997--1998 Han-Wen Nienhuys <hanwen@cs.uu.nl>
 */
 #include <stdlib.h>
 #include "rational.hh"
@@ -33,8 +33,6 @@ operator << (ostream &o, Rational r)
   return o;
 }
 
-
-
 Rational
 Rational::truncated () const
 {
@@ -43,7 +41,7 @@ Rational::truncated () const
 
 Rational::Rational ()
 {
-  sign_ = 1;
+  sign_ = 0;
   num_ = den_ = 1;
 }
 
@@ -55,6 +53,10 @@ Rational::Rational (int n, int d)
   normalise ();
 }
 
+Rational::Rational (Rational const &r)
+{
+  copy (r);
+}
 
 static
 int gcd (int a, int b)
@@ -166,38 +168,40 @@ Rational::operator += (Rational r)
  */ 
 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;
+
+      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 ();
     }
-  normalise();
 }
 
 
@@ -257,16 +261,6 @@ Rational::operator = (Rational const &r)
   return *this;
 }
 
-Rational::Rational (Rational const &r)
-{
-  copy (r);
-}
-
-Rational::operator String () const
-{
-  return str ();
-}
-
 String
 Rational::str () const
 {
@@ -275,9 +269,9 @@ Rational::str () const
       String s (sign_ > 0 ? "" : "-" );
       return String (s + "infinity");
     }
-  String s (num ());
+  String s = to_str (num ());
   if (den () != 1 && num ())
-    s += "/" + String (den ());
+    s += "/" + to_str (den ());
   return s;
 }