Re: [Matplotlib-users] How to plot Chebyshev polynolmials

[Daniel H. <dh...@gm...>]

Regardless of exactly which polynomial you are after, I've showed you how
to plot a cheb. poly.  Can you not work with the code given and plot the
exact variation of polynomial you want?



On Tue, Jan 10, 2012 at 9:46 AM, Fabien Lafont <laf...@gm...>wrote:

> No I just want to plot the third Shebitchev polynomial.
>
> 2012/1/10 Daniel Hyams <dh...@gm...>:
> > I think that you're misusing Chebyshev (do you really only want to give
> "3"
> > as a coefficient..which is just the constant function 3), and you have to
> > evaluate it in order to give matplotlib some x and y data to plot.
> >
> > from matplotlib import pyplot as plt
> > import numpy as np
> >
> > x = np.linspace(-1.0,1.0)
> > test = np.polynomial.Chebyshev((1,2,3))
> > y = test(x)
> > plt.plot(x,y)
> > plt.show()
> >
> >
> >
> > On Tue, Jan 10, 2012 at 9:10 AM, Fabien Lafont <laf...@gm...>
> > wrote:
> >>
> >> I'm trying to plot Chebyshev polynolmials using:
> >> numpy.polynomial.Chebyshev:
> >>
> >>
> >> import math
> >> from numpy import *
> >> from numpy import polynomial as pol
> >> from pylab import *
> >> from scipy import *
> >> from scipy import optimize
> >> import warnings
> >> warnings.simplefilter('ignore', np.RankWarning)
> >>
> >>
> >> test = pol.Chebyshev(3)
> >> print test
> >> plot (test)
> >>
> >>
> >> show()
> >> =======================================================================
> >>
> >> The print return:      cheb([ 3.])
> >>
> >> =======================================================================
> >> and plot :
> >>
> >>
> >> Traceback (most recent call last):
> >>  File "T:\Dropbox\Thèse\Python\fit sonde\test_poly_Tcheb.py", line
> >> 32, in <module>
> >>    plot (test)
> >>  File "C:\Python27\lib\site-packages\matplotlib\pyplot.py", line 2458,
> in
> >> plot
> >>    ret = ax.plot(*args, **kwargs)
> >>  File "C:\Python27\lib\site-packages\matplotlib\axes.py", line 3849, in
> >> plot
> >>    self.add_line(line)
> >>  File "C:\Python27\lib\site-packages\matplotlib\axes.py", line 1443,
> >> in add_line
> >>    self._update_line_limits(line)
> >>  File "C:\Python27\lib\site-packages\matplotlib\axes.py", line 1451,
> >> in _update_line_limits
> >>    p = line.get_path()
> >>  File "C:\Python27\lib\site-packages\matplotlib\lines.py", line 644,
> >> in get_path
> >>    self.recache()
> >>  File "C:\Python27\lib\site-packages\matplotlib\lines.py", line 401, in
> >> recache
> >>    y = np.asarray(yconv, np.float_)
> >>  File "C:\Python27\lib\site-packages\numpy\core\numeric.py", line
> >> 235, in asarray
> >>    return array(a, dtype, copy=False, order=order)
> >> TypeError: float() argument must be a string or a number
> >>
> >>
> >>
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> >
> >
> >
> > --
> > Daniel Hyams
> > dh...@gm...
> >
> >
> ------------------------------------------------------------------------------
> > Write once. Port to many.
> > Get the SDK and tools to simplify cross-platform app development. Create
> > new or port existing apps to sell to consumers worldwide. Explore the
> > Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join
> > http://p.sf.net/sfu/intel-appdev
> > _______________________________________________
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> >
>



-- 
Daniel Hyams
dh...@gm...