[Numpy-discussion] poly class question

Charles R Harris charlesr.harris@gmail....
Fri Oct 2 12:33:00 CDT 2009


On Fri, Oct 2, 2009 at 11:30 AM, Charles R Harris <charlesr.harris@gmail.com
> wrote:

>
>
> On Fri, Oct 2, 2009 at 11:08 AM, <josef.pktd@gmail.com> wrote:
>
>> Is there a way in numpy (or scipy) to get an infinite expansion for
>> the inverse of a polynomial (for a finite number of terms)
>>
>> np.poly1d([ -0.8, 1])**(-1)
>>
>> application for example the MA representation of an AR(1)
>>
>>
> Hmm, I've been working on a chebyshev class and division of a scalar by a
> chebyshev series is
> expressly forbidden, but it could be included if a good interface is
> proposed. Same would go for polynomials.
>

In fact is isn't hard to get, for poly1d you should be able to multiply the
series by a power of x to shift it left, then divide.

Chuck
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