forked from boostorg/integer
Merge branch 'develop' into remove_optional
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@ -9,6 +9,8 @@
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#include <limits>
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#include <stdexcept>
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#include <boost/throw_exception.hpp>
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#include <boost/core/swap.hpp>
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#include <boost/core/enable_if.hpp>
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namespace boost { namespace integer {
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@ -16,27 +18,27 @@ namespace boost { namespace integer {
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// Solves mx + ny = gcd(m,n). Returns tuple with (gcd(m,n), x, y).
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template<class Z>
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struct euclidean_result_t {
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Z gcd;
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Z x;
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Z y;
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struct euclidean_result_t
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{
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Z gcd;
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Z x;
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Z y;
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};
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template<class Z>
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euclidean_result_t<typename std::enable_if<std::numeric_limits< Z >::is_signed, Z>::type>
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typename boost::enable_if_c< std::numeric_limits< Z >::is_signed, euclidean_result_t< Z > >::type
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extended_euclidean(Z m, Z n)
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{
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if (m < 1 || n < 1)
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{
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BOOST_THROW_EXCEPTION(std::domain_error("Arguments must be strictly positive."));
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BOOST_THROW_EXCEPTION(std::domain_error("extended_euclidean: arguments must be strictly positive"));
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}
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bool swapped = false;
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if (m < n)
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{
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swapped = true;
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using std::swap;
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swap(m, n);
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swapped = true;
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boost::swap(m, n);
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}
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Z u0 = m;
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Z u1 = 1;
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@ -49,23 +51,32 @@ extended_euclidean(Z m, Z n)
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Z w2;
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while(v0 > 0)
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{
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Z q = u0/v0;
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w0 = u0 - q*v0;
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w1 = u1 - q*v1;
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w2 = u2 - q*v2;
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u0 = v0;
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u1 = v1;
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u2 = v2;
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v0 = w0;
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v1 = w1;
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v2 = w2;
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Z q = u0/v0;
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w0 = u0 - q*v0;
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w1 = u1 - q*v1;
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w2 = u2 - q*v2;
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u0 = v0;
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u1 = v1;
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u2 = v2;
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v0 = w0;
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v1 = w1;
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v2 = w2;
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}
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if (swapped)
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euclidean_result_t< Z > result;
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result.gcd = u0;
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if (!swapped)
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{
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return {u0, u2, u1};
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result.x = u1;
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result.y = u2;
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}
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return {u0, u1, u2};
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else
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{
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result.x = u2;
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result.y = u1;
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}
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return result;
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}
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}}
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@ -24,7 +24,7 @@ Z mod_inverse(Z a, Z modulus)
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{
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if (modulus < 2)
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{
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BOOST_THROW_EXCEPTION(std::domain_error("Modulus must be > 1."));
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BOOST_THROW_EXCEPTION(std::domain_error("mod_inverse: modulus must be > 1"));
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}
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// make sure a < modulus:
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a = a % modulus;
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@ -33,7 +33,7 @@ Z mod_inverse(Z a, Z modulus)
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// a doesn't have a modular multiplicative inverse:
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return 0;
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}
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euclidean_result_t<Z> u = extended_euclidean(a, modulus);
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boost::integer::euclidean_result_t<Z> u = boost::integer::extended_euclidean(a, modulus);
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if (u.gcd > 1)
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{
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return 0;
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