src/rational/division/cl_RA_ceil22.cc

   1 // ceiling2().
   2
   3 // General includes.
   4 #include "cl_sysdep.h"
   5
   6 // Specification.
   7 #include "cl_rational.h"
   8
   9
  10 // Implementation.
  11
  12 #include "cl_RA.h"
  13 #include "cl_integer.h"
  14
  15 const cl_RA_div_t ceiling2 (const cl_RA& x, const cl_RA& y)
  16 {
  17 #if 1 // Ist das wirklich schneller??
  18 // Methode:
  19 // x = a/b, y = c/d ->
  20 //   (ceiling (* a d) (* b c)) liefert q und r.
  21 //   Liefere q und r/(b*d).
  22 // x Integer -> dito mit b=1.
  23 // y Integer -> dito mit d=1.
  24 // x und y Integer -> bekannt.
  25         if (integerp(x)) {
  26                 DeclareType(cl_I,x);
  27                 if (integerp(y)) {
  28                         DeclareType(cl_I,y);
  29                         var cl_I_div_t q_r = ceiling2(x,y);
  30                         var cl_I& q = q_r.quotient;
  31                         var cl_I& r = q_r.remainder;
  32                         return cl_RA_div_t(q,r);
  33                 } else {
  34                         DeclareType(cl_RT,y);
  35                         var const cl_I& c = numerator(y);
  36                         var const cl_I& d = denominator(y);
  37                         var cl_I_div_t q_r = ceiling2(x*d,c);
  38                         var cl_I& q = q_r.quotient;
  39                         var cl_I& r = q_r.remainder;
  40                         return cl_RA_div_t(q,I_posI_div_RA(r,d));
  41                 }
  42         } else {
  43                 DeclareType(cl_RT,x);
  44                 var const cl_I& a = numerator(x);
  45                 var const cl_I& b = denominator(x);
  46                 if (integerp(y)) {
  47                         DeclareType(cl_I,y);
  48                         var cl_I_div_t q_r = ceiling2(a,b*y);
  49                         var cl_I& q = q_r.quotient;
  50                         var cl_I& r = q_r.remainder;
  51                         return cl_RA_div_t(q,I_posI_div_RA(r,b));
  52                 } else {
  53                         DeclareType(cl_RT,y);
  54                         var const cl_I& c = numerator(y);
  55                         var const cl_I& d = denominator(y);
  56                         var cl_I_div_t q_r = ceiling2(a*d,b*c);
  57                         var cl_I& q = q_r.quotient;
  58                         var cl_I& r = q_r.remainder;
  59                         return cl_RA_div_t(q,I_posI_div_RA(r,b*d));
  60                 }
  61         }
  62 #else
  63 // Methode:
  64 // ceiling2(x/y) -> (q,r). Liefere q und x-y*q=y*r.
  65         var cl_RA_div_t q_r = ceiling2(x/y);
  66         var cl_I& q = q_r.quotient;
  67         var cl_RA& r = q_r.remainder;
  68         return cl_RA_div_t(q,y*r);
  69 #endif
  70 }