[Numpy-discussion] Generating special polynomials (Chebyshev, Hermite etc.)

Kumar Appaiah a.kumar at alumni.iitm.ac.in
Fri Jun 14 20:59:03 EDT 2013

Dear Numpy Users,

I am trying to find out a way by which I can easily generate the n-th
order "special" polynomial, where "special" could refer to Hermite,
Chebyshev etc. Numpy 1.7 introduces several methods for such
polynomials, but I couldn't find a convenience function that gives me
a polynomial directly based on degree. For instance, I'd like:

hermite(3) to result in array([  0., -12.,   0.,   8.])
hermite(6) to result in array([-120.,    0.,  720.,    0., -480.,    0.,   64.])
and so on.

The quickest way I could come up with for this is:

def hermite(n):
    if n <= 0:
        return numpy.array([1.0])
    coeff_polynomial = [0.0] * n
    return numpy.polynomial.hermite.herm2poly(coeff_polynomial)

Now, if I am missing something, please let me know. If you think this
is a useful feature, I volunteer to patch all the polynomial modules
to generate such polynomials, if you could tell me appropriate
function names for such convenience functions.


Kumar Appaiah

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