[SciPy-dev] Bessel functions from Boost

Michael Abshoff michael.abshoff@googlemail....
Sun Feb 8 22:58:20 CST 2009

Robert Kern wrote:


>> I believe Ondrej was talking about using Cython to reduce call overhead,
>> not to Cythonize mpmath which might or might not pay off.
> Actually, that's all I meant by "Cythonize". You're right that it's
> not quite the right word.
>> Given that Cepehes does not do arbitrary precision taking a look at
>> mpmath before you decide to reinvent the wheel seems like a good idea.
> Actually, we weren't talking about multiprecision at all until you
> brought it up. 

Fair enough. For the Sage people the fact that Cephes is limited in 
prevision and quite buggy is a major issue. That is why we are looking 
at mpmath.

> The point of using the boost code wasn't the
> multiprecision aspect, but just that it was an alternative
> double-precision implementation that looked like it didn't have the
> bugs Cephes has.

By the way: In Sage we disabled all the special mtune and sse flags 
being set for the gfortran since it produced crashes for special 
functions all over the map on common architectures, i.e. Linux/P4 with 
gfortran 4.2.x as well as gfortran 4.3.x.

On Solaris 10 I ended up using gfortran 4.3.2 for scipy and it works 
well, i.e. no crahes while gfortran 4.2.4 and earlier was a complete and 
buggy disaster. So someone might want to put a big warning in the 
release notes or the wiki that gfortran 4.2.x and Solaris do not play 
well together with numpy as well as scipy.

> Multiprecision is an entirely different discussion, which goes some
> way towards explaining why I was confused why you and Ondrej think
> it's a good fit.

Those pesky non-engineering mathematicians and physicists :)



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