src/rational/division/cl_RA_trunc22.cc

   1 // truncate2().
   2
   3 // General includes.
   4 #include "cl_sysdep.h"
   5
   6 // Specification.
   7 #include "cln/rational.h"
   8
   9
  10 // Implementation.
  11
  12 #include "cl_RA.h"
  13 #include "cln/integer.h"
  14
  15 namespace cln {
  16
  17 const cl_RA_div_t truncate2 (const cl_RA& x, const cl_RA& y)
  18 {
  19 #if 1 // Ist das wirklich schneller??
  20 // Methode:
  21 // x = a/b, y = c/d ->
  22 //   (truncate (* a d) (* b c)) liefert q und r.
  23 //   Liefere q und r/(b*d).
  24 // x Integer -> dito mit b=1.
  25 // y Integer -> dito mit d=1.
  26 // x und y Integer -> bekannt.
  27         if (integerp(x)) {
  28                 DeclareType(cl_I,x);
  29                 if (integerp(y)) {
  30                         DeclareType(cl_I,y);
  31                         var cl_I_div_t q_r = truncate2(x,y);
  32                         var cl_I& q = q_r.quotient;
  33                         var cl_I& r = q_r.remainder;
  34                         return cl_RA_div_t(q,r);
  35                 } else {
  36                         DeclareType(cl_RT,y);
  37                         var const cl_I& c = numerator(y);
  38                         var const cl_I& d = denominator(y);
  39                         var cl_I_div_t q_r = truncate2(x*d,c);
  40                         var cl_I& q = q_r.quotient;
  41                         var cl_I& r = q_r.remainder;
  42                         return cl_RA_div_t(q,I_posI_div_RA(r,d));
  43                 }
  44         } else {
  45                 DeclareType(cl_RT,x);
  46                 var const cl_I& a = numerator(x);
  47                 var const cl_I& b = denominator(x);
  48                 if (integerp(y)) {
  49                         DeclareType(cl_I,y);
  50                         var cl_I_div_t q_r = truncate2(a,b*y);
  51                         var cl_I& q = q_r.quotient;
  52                         var cl_I& r = q_r.remainder;
  53                         return cl_RA_div_t(q,I_posI_div_RA(r,b));
  54                 } else {
  55                         DeclareType(cl_RT,y);
  56                         var const cl_I& c = numerator(y);
  57                         var const cl_I& d = denominator(y);
  58                         var cl_I_div_t q_r = truncate2(a*d,b*c);
  59                         var cl_I& q = q_r.quotient;
  60                         var cl_I& r = q_r.remainder;
  61                         return cl_RA_div_t(q,I_posI_div_RA(r,b*d));
  62                 }
  63         }
  64 #else
  65 // Methode:
  66 // truncate2(x/y) -> (q,r). Liefere q und x-y*q=y*r.
  67         var cl_RA_div_t q_r = truncate2(x/y);
  68         var cl_I& q = q_r.quotient;
  69         var cl_RA& r = q_r.remainder;
  70         return cl_RA_div_t(q,y*r);
  71 #endif
  72 }
  73
  74 }  // namespace cln