[SciPy-user] S.stats broken?

Stephen Walton stephen.walton at csun.edu
Mon Jun 20 15:12:18 CDT 2005


In the below, I've done "import scipy as S" and "import scipy.special as 
special"

In [272]:S.stats.norm.cdf(0,-4.)
Out[272]:0.999999713348

In [273]:special.ndtr(-4.)
Out[273]:3.1671241833119884e-05

If I'm reading the code correctly, S.stats.norm.cdf(0,-4) should be 
equal to special.ndtr(-4).  It is not.  Why?

lognorm.cdf is even worse.  S.stats.lognorm.cdf(1,x) returns 0.5 for any 
value of x from a small value up to and including inf.

What am I missing here?  This package can't possibly be this badly 
broken.  scipy.__version__ is 0.3.3_309.4624.



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