[SciPy-dev] Numerical stability of special functions (here: chebyu)

[Travis Oliphant]

Norbert Nemec wrote:
> Hi there,
>
> I just had my first encounter with Chebyshev polynomials of the second
> kind. A lengthy calculation could be solved very elegantly using these
> special functions. In the end, I wanted to plot the solution using
> scipy&numpy&matplotlib. To my disappointment, the results showed strong
> numerical errors, so I had to dig in deeper.
>   
The polynomials are not implemented in the best way as you've 
discovered.  This is a known problem.  We welcome any suggestions for 
improving their implementation.    Thank you for your suggestions.

-Travis