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Deleted redundant lower gamma series

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This commit is contained in:
Jacob Hass
2026-01-13 09:04:58 -08:00
parent 4e9f4410c0
commit 038cb2b887
1 changed files with 2 additions and 32 deletions
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34
include/boost/math/special_functions/gamma.hpp
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@@ -1290,37 +1290,6 @@ BOOST_MATH_GPU_ENABLED T incomplete_tgamma_large_x(const T& a, const T& x, const
return result;
}
//
// Asymptotic approximation for large a, see https://dlmf.nist.gov/8.11#E4
//
template <class T>
struct incomplete_tgamma_lower_large_a_series
{
typedef T result_type;
BOOST_MATH_GPU_ENABLED incomplete_tgamma_lower_large_a_series(const T& a, const T& x)
: a_poch(a + 1), z(x), term(1 / a) {}
BOOST_MATH_GPU_ENABLED T operator()()
{
T result = term;
term *= z / a_poch;
a_poch += 1;
return result;
}
T a_poch, z, term;
};
template <class T, class Policy>
T incomplete_tgamma_lower_large_a(const T& a, const T&x, const Policy & pol)
{
BOOST_MATH_STD_USING
incomplete_tgamma_lower_large_a_series<T> s(a, x);
boost::math::uintmax_t max_iter = boost::math::policies::get_max_series_iterations<Policy>();
T result = boost::math::tools::sum_series(s, boost::math::policies::get_epsilon<T, Policy>(), max_iter);
boost::math::policies::check_series_iterations<T>("boost::math::tgamma_p<%1%>(%1%,%1%)", max_iter, pol);
return result;
}
//
// Main incomplete gamma entry point, handles all four incomplete gamma's:
//
@@ -1860,7 +1829,8 @@ BOOST_MATH_GPU_ENABLED T lgamma_incomplete_lower_imp(T a, T x, const Policy& pol
// This still needs work...
if (a > x + 50){
return log(detail::incomplete_tgamma_lower_large_a(a, x, pol)) + a * log(x) - x - lgamma(a, pol);
std::cout << "Using approximation" << std::endl;
return log(detail::lower_gamma_series(a, x, pol)) - log(a) + a * log(x) - x - lgamma(a, pol);
}
//