[SciPy-User] special.kv goes from 0 to nan for large numbers

Johann Cohen-Tanugi johann.cohentanugi@gmail....
Mon Jan 23 17:12:18 CST 2012


Hi there, I have scipy 0.10 vanilla from the packages distributed with 
Ubuntu 11.10, and I see the following :

In [1]: import scipy

In [2]: scipy.__version__
Out[2]: '0.10.0'

In [3]: import scipy.special as sp

In [4]: sp.kv(1./3.,1.08e+09)
Out[4]: nan

In [5]: sp.kv(1./3.,1.07e+09)
Out[5]: 0.0

I guess this has to dow with a cephes and big numbers.... Is it fixed on 
github already, or is it a known bug? Or is it a feature and not a bug? 
My machine is 64bit BTW.
Best,
johann


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