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Previous commit failed for types with an extended exponent range - use logarithms rather than assuming the result is zero.

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[SVN r86346]
This commit is contained in:
John Maddock
2013-10-18 08:56:42 +00:00
parent 57b40ac443
commit 964435a350
1 changed files with 2 additions and 5 deletions
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7
include/boost/math/special_functions/bessel.hpp
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@@ -50,11 +50,8 @@ struct sph_bessel_j_small_z_series_term
mult = x / 2;
if(v + 3 > max_factorial<T>::value)
{
// term = v * log(mult) - boost::math::lgamma(v+1+T(0.5f), Policy());
// term = exp(term);
// Denominator increases faster than numerator each time v increases by one,
// so if tgamma would overflow then the result is necessarily zero.
term = 0;
term = v * log(mult) - boost::math::lgamma(v+1+T(0.5f), Policy());
term = exp(term);
}
else
term = pow(mult, T(v)) / boost::math::tgamma(v+1+T(0.5f), Policy());