[SciPy-dev] bug in scipy.stats.norm.cdf ?

John Hunter jdh2358@gmail....
Sun Mar 4 15:53:32 CST 2007


I was surprised by the nans in the cdf output below; ditto for the
survival function which is probably using the same code (svn scipy
compiled for OS X panther python2.3)

In [1]: import scipy

In [2]: import scipy.stats

In [3]: scipy.__version__
Out[3]: '0.5.3.dev2818'

In [4]: distribution = scipy.stats.norm(loc=0, scale=1)

In [5]: x = scipy.arange(-3,3,0.1)

In [6]: distribution.cdf(x)
Out[6]:
array([ 0.0013499 ,  0.00186581,  0.00255513,  0.00346697,  0.00466119,
               nan,  0.00819754,  0.01072411,  0.01390345,  0.01786442,
               nan,  0.02871656,  0.03593032,  0.04456546,  0.05479929,
               nan,  0.08075666,  0.09680048,  0.11506967,  0.13566606,
               nan,  0.18406013,  0.2118554 ,  0.24196365,  0.27425312,
               nan,  0.34457826,  0.38208858,  0.42074029,  0.46017216,
        0.5       ,  0.53982784,  0.57925971,  0.61791142,  0.65542174,
        0.69146246,  0.72574688,  0.75803635,  0.7881446 ,  0.81593987,
        0.84134475,  0.86433394,  0.88493033,  0.90319952,  0.91924334,
        0.9331928 ,  0.94520071,  0.95543454,  0.96406968,  0.97128344,
        0.97724987,  0.98213558,  0.98609655,  0.98927589,  0.99180246,
        0.99379033,  0.99533881,  0.99653303,  0.99744487,  0.99813419])

John-Hunters-Computer:~> uname -a
Darwin John-Hunters-Computer.local 7.9.0 Darwin Kernel Version 7.9.0:
Wed Mar 30 20:11:17 PST 2005; root:xnu/xnu-517.12.7.obj~1/RELEASE_PPC
Power Macintosh powerpc


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