forked from boostorg/integer
49 lines
1.5 KiB
C++
49 lines
1.5 KiB
C++
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/*
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* (C) Copyright Nick Thompson 2018.
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* Use, modification and distribution are subject to the
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* Boost Software License, Version 1.0. (See accompanying file
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* LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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*/
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#define BOOST_TEST_MODULE modular_multiplicative_inverse_test
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#include <boost/test/included/unit_test.hpp>
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#include <boost/multiprecision/cpp_int.hpp>
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#include <boost/integer/common_factor.hpp>
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#include <boost/integer/modular_multiplicative_inverse.hpp>
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using boost::multiprecision::int128_t;
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using boost::integer::modular_multiplicative_inverse;
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using boost::integer::gcd;
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template<class Z>
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void test_modular_multiplicative_inverse()
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{
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Z max_arg = 1000;
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for (Z modulus = 2; modulus < max_arg; ++modulus)
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{
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for (Z a = 1; a < max_arg; ++a)
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{
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Z gcdam = gcd(a, modulus);
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boost::optional<Z> inv_a = modular_multiplicative_inverse(a, modulus);
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// Should fail if gcd(a, mod) != 1:
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if (gcdam > 1)
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{
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BOOST_CHECK(!inv_a);
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}
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else
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{
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BOOST_CHECK(inv_a.value() > 0);
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Z outta_be_one = (inv_a.value()*a) % modulus;
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BOOST_CHECK_EQUAL(outta_be_one, 1);
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}
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}
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}
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}
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BOOST_AUTO_TEST_CASE(extended_euclidean_test)
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{
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test_modular_multiplicative_inverse<int>();
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test_modular_multiplicative_inverse<long>();
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test_modular_multiplicative_inverse<long long>();
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test_modular_multiplicative_inverse<int128_t>();
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}
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