[Tutor] ploting of a square well

[Debashish Saha]

---------- Forwarded message ----------
From: Debashish Saha <silideba at gmail.com>
Date: Sun, Feb 5, 2012 at 7:08 PM
Subject: ploting of a square well
To: tutor at python.org


from pylab import *
x=linspace(1,1000,10000)
a,b = 10,20
def v(x):
   i=5;v0=2
   for n in range(1,1+i):
       if x>(n-1)*(a+b) and x<a+(n-1)*(a+b):
           return 0
       elif x>a+(n-1)*(a+b) and x<(n)*(a+b) :
           return v0
#v=vectorize(v)
plot(x,v)
show()

Error:
ValueError                                Traceback (most recent call last)
C:\Python27\lib\site-packages\IPython\utils\py3compat.pyc in
execfile(fname, glob, loc)
    166             else:
    167                 filename = fname
--> 168             exec compile(scripttext, filename, 'exec') in glob, loc
    169     else:
    170         def execfile(fname, *where):

C:\Users\as\klj.py in <module>()
     10            return v0
     11 #v=vectorize(v)

---> 12 plot(x,v)
     13 show()

C:\Python27\lib\site-packages\matplotlib\pyplot.pyc in plot(*args, **kwargs)
   2456         ax.hold(hold)
   2457     try:
-> 2458         ret = ax.plot(*args, **kwargs)
   2459         draw_if_interactive()
   2460     finally:

C:\Python27\lib\site-packages\matplotlib\axes.pyc in plot(self, *args, **kwargs)
   3846         lines = []
   3847
-> 3848         for line in self._get_lines(*args, **kwargs):
   3849             self.add_line(line)
   3850             lines.append(line)

C:\Python27\lib\site-packages\matplotlib\axes.pyc in
_grab_next_args(self, *args, **kwargs)
    321                 return
    322             if len(remaining) <= 3:
--> 323                 for seg in self._plot_args(remaining, kwargs):
    324                     yield seg
    325                 return

C:\Python27\lib\site-packages\matplotlib\axes.pyc in _plot_args(self,
tup, kwargs)
    298             x = np.arange(y.shape[0], dtype=float)
    299
--> 300         x, y = self._xy_from_xy(x, y)
    301
    302         if self.command == 'plot':

C:\Python27\lib\site-packages\matplotlib\axes.pyc in _xy_from_xy(self, x, y)
    238         y = np.atleast_1d(y)
    239         if x.shape[0] != y.shape[0]:
--> 240             raise ValueError("x and y must have same first dimension")
    241         if x.ndim > 2 or y.ndim > 2:
    242             raise ValueError("x and y can be no greater than 2-D")

ValueError: x and y must have same first dimension
Question:
what is to be edited?