[SciPy-Dev] cephes_smirnov never returns on mips/sparc/...

josef.pktd@gmai... josef.pktd@gmai...
Fri Mar 30 11:33:56 CDT 2012


On Fri, Mar 30, 2012 at 11:43 AM, Yaroslav Halchenko
<lists@onerussian.com> wrote:
> I have reported this issue some time ago on Debian
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=653948
> and then forgot about it until now that I ran into it again.
>
> With recent scipy (including git master 0fbfdbc)
>
> scipy.stats.ksone.fit
>
> seems to stall (never return) on big-endian boxes and return (1.0, nan,
> nan) on x86.  It seems that it is  working correctly with scipy
> 0.7.2 (as it is now in Debian stable).
>
> So -- is that anything known?

No, never seen before.

I didn't think anyone would ever fit ksone, It doesn't even have a pdf
defined in the source. It's mainly included for Kolmogorov-Smirnov
test.


I don't know how to interpret gdp. Is it clear that it is
cephes_smirnov? Do you know the values that trigger it?
If not, you could put a print in the ksone_gen._cdf to see where it
gets stuck. (it might print a lot)

I think it's a bug for scipy.stats that ksone doesn't define the
support boundary .b, it looks like it should be (0,1) (default a=0
looks ok.)
There will be lots of nans during fit().  I don't think the generic
fit is smart enough to figure out non-nan or non-inf starting values
for your dataset. (There is a ticket to avoid inf in starting values
but it hasn't been included yet.)

Josef

>
> snippet to replicate:
>
> import numpy as np
> import scipy.stats as ss
>
>
> d = np.array([-0.18879233,  0.15734249,  0.18695107,  0.27908787, -0.248649,
>              -0.2171497 ,  0.12233512,  0.15126419,  0.03119282,  0.4365294 ,
>              0.08930393, -0.23509903,  0.28231224, -0.09974875, -0.25196048,
>              0.11102028,  0.1427649 ,  0.10176452,  0.18754054,  0.25826724,
>              0.05988819,  0.0531668 ,  0.21906056,  0.32106729,  0.2117662 ,
>              0.10886442,  0.09375789,  0.24583286, -0.22968366, -0.07842391,
>              -0.31195432, -0.21271196,  0.1114243 , -0.13293002,  0.01331725,
>              -0.04330977, -0.09485776, -0.28434547,  0.22245721, -0.18518199,
>              -0.10943985, -0.35243174,  0.06897665, -0.03553363, -0.0701746 ,
>              -0.06037974,  0.37670779, -0.21684405])
>
> print "Fitting now"
> print ss.ksone.fit(d)
>
>
> --
> =------------------------------------------------------------------=
> Keep in touch                                     www.onerussian.com
> Yaroslav Halchenko                 www.ohloh.net/accounts/yarikoptic
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