/* * (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 #include #include #include using boost::multiprecision::int128_t; using boost::multiprecision::int256_t; using boost::integer::mod_inverse; using boost::integer::gcd; template void test_mod_inverse() { std::cout << "Testing the modular multiplicative inverse on type " << boost::typeindex::type_id().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 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(); test_mod_inverse(); test_mod_inverse(); test_mod_inverse(); test_mod_inverse(); test_mod_inverse(); }