On Fri, Apr 2, 2010 at 11:27 AM, David Goldsmith <d.l.goldsm...@gmail.com>wrote:
> On Thu, Apr 1, 2010 at 6:42 PM, David Goldsmith > <d.l.goldsm...@gmail.com>wrote: > >> >>> 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. >> > > Also: > > >>> c.deriv(0) > Chebyshev([ 1.], [-1., 1.]) > >>> c.integ(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 > 729, > in chebint > raise ValueError, "The order of integration must be positive" > ValueError: The order of integration must be positive > > i.e., deriv supports zero-order differentiation, but integ doesn't support > zero-order integration (though I acknowledge that this may be a feature, not > a bug). > > It was inherited. I have no qualms about letting it integrate zero times if folks think it should go that way. I think the reason derivatives allowed 0 for the number of derivations was for classroom instruction. Chuck > >
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