Changeset 6c6455f for src/libcfa

Timestamp:

May 15, 2017, 10:08:23 PM (8 years ago)

Author:

Peter A. Buhr <pabuhr@…>

Branches:

ADT, aaron-thesis, arm-eh, ast-experimental, cleanup-dtors, deferred_resn, demangler, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, new-env, no_list, persistent-indexer, pthread-emulation, qualifiedEnum, resolv-new, with_gc

Children:

22634b2

Parents:

9ebd778

Message:

second attempt at generic rational type with conversions to/from floating point

Location:

src/libcfa

Files:

• rational (modified) (2 diffs)
• rational.c (modified) (2 diffs)

src/libcfa/rational

@@ -12 +12 @@
 // Created On       : Wed Apr  6 17:56:25 2016
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Sun May 14 16:49:13 2017
-// Update Count     : 78
+// Last Modified On : Mon May 15 21:30:12 2017
+// Update Count     : 90
 //
 
@@ -128 +128 @@
 
 // conversion
-// forall ( otype RationalImpl | arithmetic( RationalImpl ) )
-// double widen( Rational(RationalImpl) r );
-// forall ( otype RationalImpl | arithmetic( RationalImpl ) )
-// Rational(RationalImpl) narrow( double f, RationalImpl md );
+forall ( otype RationalImpl | arithmetic( RationalImpl ) | { double convert( RationalImpl ); } )
+double widen( Rational(RationalImpl) r );
+forall ( otype RationalImpl | arithmetic( RationalImpl ) | { double convert( RationalImpl );  RationalImpl convert( double );} )
+Rational(RationalImpl) narrow( double f, RationalImpl md );
 
 // I/O

src/libcfa/rational.c

@@ -10 +10 @@
 // Created On       : Wed Apr  6 17:54:28 2016
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Sun May 14 17:25:19 2017
-// Update Count     : 131
+// Last Modified On : Mon May 15 21:29:23 2017
+// Update Count     : 149
 // 
 
@@ -190 +190 @@
 // conversion
 
-// forall ( otype RationalImpl | arithmetic( RationalImpl ) )
-// double widen( Rational(RationalImpl) r ) {
-//      return (double)r.numerator / (double)r.denominator;
-// } // widen
-
-// // http://www.ics.uci.edu/~eppstein/numth/frap.c
-// forall ( otype RationalImpl | arithmetic( RationalImpl ) )
-// Rational(RationalImpl) narrow( double f, RationalImpl md ) {
-//      if ( md <= 1 ) {                                                                        // maximum fractional digits too small?
-//              return (Rational(RationalImpl)){ f, 1};                 // truncate fraction
-//      } // if
-
-//      // continued fraction coefficients
-//      RationalImpl m00 = 1, m11 = 1, m01 = 0, m10 = 0;
-//      RationalImpl ai, t;
-
-//      // find terms until denom gets too big
-//      for ( ;; ) {
-//              ai = (RationalImpl)f;
-//        if ( ! (m10 * ai + m11 <= md) ) break;
-//              t = m00 * ai + m01;
-//              m01 = m00;
-//              m00 = t;
-//              t = m10 * ai + m11;
-//              m11 = m10;
-//              m10 = t;
-//              t = (double)ai;
-//        if ( f == t ) break;                                                          // prevent division by zero
-//        f = 1 / (f - (double)t);
-//        if ( f > (double)0x7FFFFFFF ) break;                          // representation failure
-//      } 
-//      return (Rational(RationalImpl)){ m00, m10 };
-// } // narrow
+forall ( otype RationalImpl | arithmetic( RationalImpl ) | { double convert( RationalImpl ); } )
+double widen( Rational(RationalImpl) r ) {
+        return convert( r.numerator ) / convert( r.denominator );
+} // widen
+
+// http://www.ics.uci.edu/~eppstein/numth/frap.c
+forall ( otype RationalImpl | arithmetic( RationalImpl ) | { double convert( RationalImpl ); RationalImpl convert( double ); } )
+Rational(RationalImpl) narrow( double f, RationalImpl md ) {
+        if ( md <= (RationalImpl){1} ) {                                        // maximum fractional digits too small?
+                return (Rational(RationalImpl)){ convert( f ), (RationalImpl){1}}; // truncate fraction
+        } // if
+
+        // continued fraction coefficients
+        RationalImpl m00 = {1}, m11 = { 1 }, m01 = { 0 }, m10 = { 0 };
+        RationalImpl ai, t;
+
+        // find terms until denom gets too big
+        for ( ;; ) {
+                ai = convert( f );
+          if ( ! (m10 * ai + m11 <= md) ) break;
+                t = m00 * ai + m01;
+                m01 = m00;
+                m00 = t;
+                t = m10 * ai + m11;
+                m11 = m10;
+                m10 = t;
+                double temp = convert( ai );
+          if ( f == temp ) break;                                                       // prevent division by zero
+                f = 1 / (f - temp);
+          if ( f > (double)0x7FFFFFFF ) break;                          // representation failure
+        } // for
+        return (Rational(RationalImpl)){ m00, m10 };
+} // narrow