[Numpy-discussion] Asymmetry in Chebyshev.deriv v. Chebyshev.integ

David Goldsmith d.l.goldsmith at gmail.com
Thu Apr 1 21:42:23 EDT 2010


>>> np.version.version
'1.4.0'
>>> c = np.polynomial.chebyshev.Chebyshev(1)
>>> c.deriv(1.0)
Chebyshev([ 0.], [-1.,  1.])
>>> c.integ(1.0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 441, in integ
  File "C:\Python26\lib\site-packages\numpy\polynomial\chebyshev.py", line
739,
in chebint
    k = list(k) + [0]*(m - len(k))
TypeError: can't multiply sequence by non-int of type 'float'
>>> c.integ(1)
Chebyshev([ 0.,  1.], [-1.,  1.])

i.e., deriv accepts int_like input but integ doesn't.

Given the way I just embarrassed myself on the scipy-dev list :-(, I'm
confirming this is a bug before I file a ticket.

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