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Remove inferior generalized gcd; include integral size promotion.

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This commit is contained in:
Jeremy W. Murphy
2016-04-20 22:53:56 +10:00
parent dc81bc8e6e
commit d484fa657c
2 changed files with 30 additions and 48 deletions
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67
include/boost/math/tools/polynomial.hpp
View File

@@ -16,12 +16,14 @@
#include <boost/assert.hpp>
#include <boost/config.hpp>
#include <boost/function.hpp>
#include <boost/integer.hpp>
#include <boost/lambda/lambda.hpp>
#include <boost/math/tools/rational.hpp>
#include <boost/math/tools/real_cast.hpp>
#include <boost/math/special_functions/binomial.hpp>
#include <boost/operators.hpp>
#include <boost/math/common_factor_rt.hpp>
#include <boost/mpl/if.hpp>
#include <boost/operators.hpp>
#include <vector>
#include <ostream>
@@ -663,19 +665,33 @@ namespace detail
/* 4.6.1C: Greatest common divisor over a unique factorization domain.
*
* Although step C3 keeps the coefficients to a "reasonable" size, they are
* still potentially several binary orders of magnitude larger than the inputs.
*/
template <class T>
typename enable_if_c< std::numeric_limits<T>::is_integer, polynomial<T> >::type
gcd_ufd(polynomial<T> u, polynomial<T> v)
gcd_ufd(polynomial<T> const &a, polynomial<T> const &b)
{
BOOST_ASSERT(u);
BOOST_ASSERT(v);
BOOST_ASSERT(a);
BOOST_ASSERT(b);
typedef typename polynomial<T>::size_type N;
// If T is a POD, double the output size, otherwise assume it is multi-prec.
// This precludes the use of long as a coefficient type in combination with
// gcd.
/*
typedef typename mpl::if_<is_pod<T>,
typename mpl::if_<is_unsigned<T>,
typename uint_t<sizeof(T) * 16>::fast,
typename int_t<sizeof(T) * 16>::fast >::type,
T>::type U;
*/
typedef T U;
using boost::math::gcd;
T const d = detail::reduce_to_primitive(u, v);
T g = 1, h = 1;
polynomial<T> r;
polynomial<U> u(a), v(b);
U const d = detail::reduce_to_primitive(u, v);
U g = 1, h = 1;
polynomial<U> r;
while (true)
{
// Pseudo-division.
@@ -685,7 +701,7 @@ gcd_ufd(polynomial<T> u, polynomial<T> v)
goto gcd_end;
if (r.degree() == 0)
{
v = polynomial<T>(T(1));
v = polynomial<U>(U(1));
goto gcd_end;
}
// Adjust remainder.
@@ -703,41 +719,6 @@ gcd_end:
return d * primitive_part(v);
}
// Knuth, 4.6.1E
template <class T>
typename enable_if_c< std::numeric_limits<T>::is_integer, polynomial<T> >::type
generalized_gcd(polynomial<T> u, polynomial<T> v)
{
BOOST_ASSERT(u);
BOOST_ASSERT(v);
using boost::math::gcd;
// Reduce to primitive.
T const d = detail::reduce_to_primitive(u, v);
polynomial<T> r;
while (true)
{
// Pseudo-division.
r = u % v;
if (!r)
goto gcd_end;
if (r.degree() == 0)
{
v = polynomial<T>(T(1));
goto gcd_end;
}
// Make remainder primitive.
u = v;
v = primitive_part(r);
}
gcd_end:
return d * v;
}
template <class T>
typename enable_if_c< std::numeric_limits<T>::is_integer, polynomial<T> >::type
gcd(polynomial<T> const &u, polynomial<T> const &v)

11
test/test_polynomial.cpp
View File

@@ -224,14 +224,17 @@ BOOST_AUTO_TEST_CASE_TEMPLATE(test_cont_and_pp, T, integral_test_types)
BOOST_CHECK_EQUAL(a, content(a) * primitive_part(a));
}
BOOST_AUTO_TEST_CASE_TEMPLATE(test_gcd_ufd, T, integral_test_types)
typedef boost::mpl::list<short, int> sp_integral_gcd_test_types;
typedef boost::mpl::joint_view<sp_integral_gcd_test_types, mp_integral_test_types> integral_gcd_test_types;
BOOST_AUTO_TEST_CASE_TEMPLATE(test_gcd_ufd, T, sp_integral_gcd_test_types)
{
polynomial<T> const a(d8.begin(), d8.end());
polynomial<T> const b(d6.begin(), d6.end());
polynomial<T> d = gcd_ufd(a, b);
BOOST_CHECK_EQUAL(d, polynomial<T>(1));
d = generalized_gcd(a, b);
BOOST_CHECK_EQUAL(d, polynomial<T>(1));
boost::array<T, 5> const i4a = {{105, 278, -88, -56, 16}};
boost::array<T, 5> const i4b = {{70, 232, -44, -64, 16}};
@@ -241,6 +244,4 @@ BOOST_AUTO_TEST_CASE_TEMPLATE(test_gcd_ufd, T, integral_test_types)
polynomial<T> const w(i2.begin(), i2.end());
d = gcd_ufd(u, v);
BOOST_CHECK_EQUAL(d, w);
polynomial<T> d_g = generalized_gcd(u, v);
BOOST_CHECK_EQUAL(d, w);
}