Re: [Matplotlib-users] Plotting Continuous Functions

On Sun, 25 Nov 2007, Angus McMorland wrote:

> I'm not completely sure, but I suspect that this is an implementation bug,
> rather than a version bug, particularly because the line in question isn't
> involving matplotlib at all. If you post the relevant code
> (normal-curve.py, by the looks of things), it might be easy to spot the
> problem.

Angus,

   I've seen the same error trying to plot other curves in the past couple of
days, but not those using the Boltzmann distribution. Here's the file:

import matplotlib.numerix as nx
import pylab as p
from math import *

center = 50.0
fwhm = 50.0

def fwhm2k(fwhm):
   '''converts fwhm value to k (see above)'''
   return fwhm/(2 * nx.sqrt(nx.log(2)))

def gauss1d(r, fwhm, center):
   '''returns the 1d gaussian given by fwhm (full-width at half-max),
   and c (centre) at positions given by r
   '''
   return exp(-(r-center)**2 / fwhm2k(fwhm)**2)

x = nx.arange(0, 100, 0.1)
G = gauss1d(x, fwhm, center)
p.plot(x, G, color='red', lw=2)
p.axis([0, 100, 0.0, 1.0])
p.xlabel('Universe of Discourse')
p.ylabel('Membership Grade')
p.show()

> I've found it easiest to solve these sorts of bugs by running the code in
> an ipython shell, with automatic pdb calling. That way you can inspect the
> values of the parameters in question - one of which is, I think, the
> problem here.

   I've not run ipython with pdb; I'll look at the docs to learn how. I do
use winpdb on the application.

Thanks,

Rich

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