DGtal  0.9.3
Functions
extended-euclid.cpp File Reference
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <iomanip>
#include <string>
#include "DGtal/arithmetic/IntegerComputer.h"
Include dependency graph for extended-euclid.cpp:

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Functions

void usage (int, char **argv)
 
int main (int argc, char **argv)
 

Detailed Description

Author
Jacques-Olivier Lachaud (jacqu.nosp@m.es-o.nosp@m.livie.nosp@m.r.la.nosp@m.chaud.nosp@m.@uni.nosp@m.v-sav.nosp@m.oie..nosp@m.fr ) Laboratory of Mathematics (CNRS, UMR 5127), University of Savoie, France
Date
2012/02/06

An example file named extended-euclid.

This file is part of the DGtal library.

Definition in file extended-euclid.cpp.

Function Documentation

◆ main()

int main ( int  argc,
char **  argv 
)

Main.

[extended-euclid-types]

[extended-euclid-types]

[extended-euclid-instantiation]

[extended-euclid-instantiation]

[extended-euclid-process]

[extended-euclid-process]

Definition at line 57 of file extended-euclid.cpp.

References usage().

58 {
59  if ( argc < 4 )
60  {
61  usage( argc, argv );
62  return 0;
63  }
64 
66  typedef BigInteger Integer;
67  typedef IntegerComputer<Integer> IC;
69 
71  Integer a( argv[ 1 ] );
72  Integer b( argv[ 2 ] );
73  Integer c( argv[ 3 ] );
74  IC ic;
75  Integer g = ic.gcd( a, b );
76  if ( ic.isZero( a ) || ic.isZero( b ) )
77  {
78  std::cerr << "[Error] parameters a and b should be non-null." << std::endl;
79  return 1;
80  }
81  if ( ic.isNotZero( c % g ) )
82  {
83  std::cerr << "[Error] parameter c should be a multiple of gcd(a,b)." << std::endl;
84  return 2;
85  }
87 
89  IC::Vector2I X = ic.extendedEuclid( a, b, c );
90  std::cout << "x=" << X[ 0 ] << " y=" << X[ 1 ] << std::endl;
91  Integer d = a*X[ 0 ] + b*X[ 1 ];
92  if ( c != d )
93  {
94  std::cerr << "[Internal Error] Output of extended Euclid algorithm is incorrect: " << d << " != " << c
95  << ". This should not happen." << std::endl;
96  return 3;
97  }
99  return 0;
100 }
DGtal::int32_t Integer
Definition: StdDefs.h:74
mpz_class BigInteger
Multi-precision integer with GMP implementation.
Definition: BasicTypes.h:79
void usage(int, char **argv)

◆ usage()

void usage ( int  ,
char **  argv 
)

Definition at line 47 of file extended-euclid.cpp.

Referenced by main().

48 {
49  std::cerr << "Usage: " << argv[ 0 ] << " <a> <b> <c>" << std::endl;
50  std::cerr << "\t - solves the diophantine equation ax+by=c by the extended Euclid algorithm." << std::endl;
51  std::cerr << "\t - note: c should be a multiple of gcd(a,b)." << std::endl;
52 }