[Numpy-discussion] Strange behavior of np.sinc

David Goldsmith d.l.goldsmith@gmail....
Sun Jun 27 00:00:56 CDT 2010


On Sat, Jun 26, 2010 at 9:39 PM, Robert Kern <robert.kern@gmail.com> wrote:

> On Sat, Jun 26, 2010 at 23:33, David Goldsmith <d.l.goldsmith@gmail.com>
> wrote:
> > 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)?
>
> Bug in both code and docs. There should be an "x = np.asanyarray(x)"
> before the rest of the code.
>

Thanks Robert; I'll file a ticket and fix the docstring.

DG
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