arithmetic/fraction.cpp

Computes a fraction from its quotients.

See also

Fractions are back insertable

# More precise approximation of pi
$ ./examples/arithmetic/fraction 3 7 15 1 292 1 1 1 2 1 3 1 14
z = 80143857 / 25510582

 
#include <iostream>
#include "DGtal/arithmetic/LighterSternBrocot.h"
 
 
using namespace DGtal;
 
 
void usage( int, char** argv )
{
  std::cerr << "Usage: " << argv[ 0 ] << " <u_0> <u_1> ... <u_k>" << std::endl;
  std::cerr << "\t - computes the fraction [u_0; u_1, ..., u_k] from its partial quotients." << std::endl;
}
 
int main( int argc, char** argv )
{
  if ( argc < 3 )
    {
      usage( argc, argv );
      return 1;
    }
 
  typedef DGtal::int64_t Integer;
  typedef DGtal::int64_t Quotient;
  typedef LighterSternBrocot<Integer, Quotient, StdMapRebinder> SB; // the type of the Stern-Brocot tree
  typedef SB::Fraction Fraction; // the type for fractions
  typedef std::back_insert_iterator< Fraction > OutputIterator;
 
  Fraction f;
  OutputIterator itback = std::back_inserter( f );
  for ( Quotient i = 1; i < argc; ++i)
    {
      Quotient u = atoll( argv[ i ] );
      *itback++ = std::make_pair( u, i-1 );
    }
  std::cout << "z = " << f.p() << " / " << f.q() << std::endl;
  return 0;
}