forked from boostorg/integer
53 lines
1.6 KiB
C++
53 lines
1.6 KiB
C++
/*
|
|
* (C) Copyright Nick Thompson 2018.
|
|
* Use, modification and distribution are subject to the
|
|
* Boost Software License, Version 1.0. (See accompanying file
|
|
* LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
|
|
*/
|
|
#define BOOST_TEST_MODULE mod_inverse_test
|
|
#include <boost/test/included/unit_test.hpp>
|
|
#include <boost/multiprecision/cpp_int.hpp>
|
|
#include <boost/integer/common_factor.hpp>
|
|
#include <boost/integer/mod_inverse.hpp>
|
|
|
|
using boost::multiprecision::int128_t;
|
|
using boost::multiprecision::int256_t;
|
|
using boost::integer::mod_inverse;
|
|
using boost::integer::gcd;
|
|
|
|
template<class Z>
|
|
void test_mod_inverse()
|
|
{
|
|
std::cout << "Testing the modular multiplicative inverse on type " << boost::typeindex::type_id<Z>().pretty_name() << "\n";
|
|
Z max_arg = 1000;
|
|
for (Z modulus = 2; modulus < max_arg; ++modulus)
|
|
{
|
|
for (Z a = 1; a < max_arg; ++a)
|
|
{
|
|
Z gcdam = gcd(a, modulus);
|
|
boost::optional<Z> inv_a = mod_inverse(a, modulus);
|
|
// Should fail if gcd(a, mod) != 1:
|
|
if (gcdam > 1)
|
|
{
|
|
BOOST_CHECK(!inv_a);
|
|
}
|
|
else
|
|
{
|
|
BOOST_CHECK(inv_a.value() > 0);
|
|
Z outta_be_one = (inv_a.value()*a) % modulus;
|
|
BOOST_CHECK_EQUAL(outta_be_one, 1);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
BOOST_AUTO_TEST_CASE(mod_inverse_test)
|
|
{
|
|
test_mod_inverse<short int>();
|
|
test_mod_inverse<int>();
|
|
test_mod_inverse<long>();
|
|
test_mod_inverse<long long>();
|
|
test_mod_inverse<int128_t>();
|
|
test_mod_inverse<int256_t>();
|
|
}
|