Re: [Matplotlib-users] Fit with Chebyshev Polynomials

[Benjamin R. <ben...@ou...>]

On Wednesday, December 14, 2011, Fabien Lafont <laf...@gm...>
wrote:
> I have a basic problem (I think)
>
> I try to fit some data with this function
>
http://docs.scipy.org/doc/numpy/reference/generated/numpy.polynomial.Chebyshev.fit.html
>
> But it return an error:
>
> fit = chebyshev.fit(T,R,3)
> NameError: name 'chebyshev' is not defined
>
> I don't understand I've imported Numpy and polynomials... An Idea?
>
>
> import math
> from numpy import *
> from numpy import polynomial
> from pylab import *
> from scipy import *
> from scipy import optimize
> import warnings
> warnings.simplefilter('ignore', np.RankWarning)
>
>
> R = [ 9011.5   ,  7822.7   ,  6253.9   ,  4877.56  ,  3892.08  ,
> 3221.41  ,  2647.05,
>  2260.94 ,   1959.72  ,  1712.06   , 1522.28  ,  1367.87  ,  1242.953
>  , 1185.092,
>  1104.452  , 1031.862  ,  919.8644  , 832.9942  , 767.8944  , 715.1569,
>   671.6301 ,  635.1634 ,  604.284   , 577.5536]
>
> T = range(0,len(R))
> plot (T,R,".")
> show()
> fit = chebyshev.fit(T,R,3)
> print fit
>

The function would be in the "polynomial" namespace.  So
"polynomial.chebyshev()" would work.  To reduce typing, you can import a
module "as" some other name.

from numpy import polynomial as poly

..

fit = poly.chebyshev.fit(T,R,3)

Importing modules is very flexible and I suggest reading up on it.

Ben Root