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[polygamma] Switch to new better method for handling negative arguments.

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This commit is contained in:
jzmaddock
2014-11-17 18:12:25 +00:00
parent 26f063eca4
commit f4b86c2996
2 changed files with 40 additions and 12 deletions
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23
include/boost/math/special_functions/detail/polygamma.hpp
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@@ -497,6 +497,7 @@
int index = n - 1;
#if 0
if(index >= (int)table.size())
{
//
@@ -522,8 +523,8 @@
}
}
T sum = 0;
int power = n & 1 ? 0 : 1;
T sum = 0;
//
// Compute the sum of the cosine terms:
//
@@ -532,6 +533,24 @@
sum += table[index][j] * boost::math::cos_pi(x * power, pol);
power += 2;
}
#else
if(index >= (int)table.size())
{
for(int i = (int)table.size() - 1; i < index; ++i)
{
int sin_order = i + 2;
table.push_back(std::vector<T>(i + 2, T(0)));
table[i + 1][1] -= sin_order * table[i][0] / (sin_order - 1);
for(int cos_order = 1; cos_order < i + 1; ++cos_order)
{
table[i + 1][cos_order + 1] += ((cos_order - sin_order) * table[i][cos_order]) / (sin_order - 1);
table[i + 1][cos_order - 1] += (-cos_order * table[i][cos_order]) / (sin_order - 1);
}
}
}
T sum = boost::math::tools::evaluate_polynomial(&table[index][0], boost::math::cos_pi(x, pol), n);
#endif
if(sum == 0)
return sum;
//
@@ -542,7 +561,7 @@
if(s == 0)
return sum * boost::math::policies::raise_overflow_error<T>(function, 0, pol);
power_terms -= log(fabs(s)) * (n + 1);
power_terms += boost::math::lgamma(T(n + 1));
power_terms += boost::math::lgamma(T(n));
power_terms += log(fabs(sum));
if(power_terms > boost::math::tools::log_max_value<T>())

29
test/test_polygamma.hpp
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