I'm not used to reply-all
---------- Forwarded message ----------
From: <josef.p...@gmail.com>
Date: Tue, Jan 10, 2012 at 10:20 AM
Subject: Re: [Matplotlib-users] How to plot Chebyshev polynolmials
To: Fabien Lafont <lafont.fab...@gmail.com>
On Tue, Jan 10, 2012 at 9:46 AM, Fabien Lafont <lafont.fab...@gmail.com> wrote:
> No I just want to plot the third Shebitchev polynomial.
the vander functions give you the basis functions for a given x, or
use coefficients only for the polynomial you want, if I understand
correctly what you want
>>> import numpy as np
>>> from numpy import polynomial as poly
>>> chebs = [poly.Chebyshev(coef) for coef in np.eye(5)]
>>> for p in chebs: plt.plot(x, p(x))
...
[<matplotlib.lines.Line2D object at 0x046D91F0>]
[<matplotlib.lines.Line2D object at 0x046D9510>]
[<matplotlib.lines.Line2D object at 0x046D9830>]
[<matplotlib.lines.Line2D object at 0x046D9B50>]
[<matplotlib.lines.Line2D object at 0x046D9E70>]
>>> plt.show()
or
>>> plt.plot(poly.chebvander(x, 5))
Josef
>
> 2012/1/10 Daniel Hyams <dhy...@gmail.com>:
>> 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 <lafont.fab...@gmail.com>
>> 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
>> dhy...@gmail.com
>>
>> ------------------------------------------------------------------------------
>> 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
>> _______________________________________________
>> Matplotlib-users mailing list
>> Matplotlib-users@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>
>
> ------------------------------------------------------------------------------
> 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
> _______________________________________________
> Matplotlib-users mailing list
> Matplotlib-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
------------------------------------------------------------------------------
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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