[Numpy-discussion] Strange behavior of np.sinc

David Goldsmith d.l.goldsmith@gmail....
Sat Jun 26 23:33:47 CDT 2010


Hi!  The docstring for numpy.lib.function_base.sinc indicates that the
parameter has to be an ndarray, and that it will return the limiting value 1
for sinc(0).  Checking to see if it should actually say array_like, I found
the following (Python 2.6):

>>> np.sinc(np.array((0,0.5)))
array([ 1.        ,  0.63661977])
>>> np.sinc((0,0.5))
array([        NaN,  0.63661977])
>>> np.sinc([0,0.5])
array([        NaN,  0.63661977])
>>> np.version.version
'1.4.1'

So, it doesn't choke on non-array sequences, and appears to return values
consistent w/ array input, except at 0.  Bug in code (failure at 0 if in a
sequence) and in the doc (ndarray should be array_like)?

DG
-- 
Mathematician: noun, someone who disavows certainty when their uncertainty
set is non-empty, even if that set has measure zero.

Hope: noun, that delusive spirit which escaped Pandora's jar and, with her
lies, prevents mankind from committing a general suicide.  (As interpreted
by Robert Graves)
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