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

 Re: [Matplotlib-users] How to plot Chebyshev polynolmials From: Daniel Hyams - 2012-01-10 14:34:31 Attachments: Message as HTML 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 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 > 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 > > > ------------------------------------------------------------------------------ > 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@... > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > -- Daniel Hyams dhyams@...