problems with semilogy and debian

Hi there
I use matplotlib from within ipyton (simply by calling $ipython -pylab
in a shell window). I'm using the debian packages as mentioned on the
matplotlib homepage on a Debian sarge system.
Everything works fine except the semilogy command behaves a bit strange
(I'm new to matplotlib so it is maybe my mistake).
After starting ipython in pylab mode I do the following:

In [1]: x=arrayrange(0.0,100.0);

In [2]: plot(x)
Out[2]: [<matplotlib.lines.Line2D instance at 0x4437a30c>]

until here everything works fine (I use the TkAgg interface for
interactive plotting, hold is set to False).
If I continue now with

In [3]: semilogy(x)


ValueError Traceback (most recent call


/usr/lib/python2.3/site-packages/matplotlib/ in semilogy(*args,
   2089 hold(b)
   2090 else:
-> 2091 draw_if_interactive()
   2093 hold(b)

/usr/lib/python2.3/site-packages/matplotlib/backends/ in
     39 def draw_if_interactive():
     40 draw_if_interactive._called = True
---> 41 __draw_int()
     42 # Flag to store state, so external callers (like ipython)
can keep track
     43 # of draw calls.

/usr/lib/python2.3/site-packages/matplotlib/backends/ in
     56 figManager = Gcf.get_active()
     57 if figManager is not None:
---> 58

/usr/lib/python2.3/site-packages/matplotlib/backends/ in
    275 # requires this
    276 if sys.platform=='win32' : self.window.update()
--> 277 else: self.canvas.draw()
    278 self._shown = True

/usr/lib/python2.3/site-packages/matplotlib/backends/ in
    141 def draw(self):
--> 142 FigureCanvasAgg.draw(self)
    143 tkagg.blit(self._tkphoto, self.renderer._renderer, 2)
    144 self._master.update_idletasks()

/usr/lib/python2.3/site-packages/matplotlib/backends/ in
    306 self.renderer = RendererAgg(w, h, self.figure.dpi)
    307 self._lastKey = key
--> 308 self.figure.draw(self.renderer)
    310 def tostring_rgb(self):

/usr/lib/python2.3/site-packages/matplotlib/ in draw(self,
    333 # render the axes
--> 334 for a in self.axes: a.draw(renderer)
    336 # render the figure text

/usr/lib/python2.3/site-packages/matplotlib/ in draw(self,
   1167 if not self.get_visible(): return
   1168 renderer.open_group('axes')
-> 1169 self.transData.freeze() # eval the lazy objects
   1170 self.transAxes.freeze() # eval the lazy objects
   1171 if self.axison:

ValueError: Cannot take log of nonpositive value

you see what happens. Since the array starts with 0.0 the error message
is ok. But

In [4]: x=x+1.0;

In [5]: semilogy(x)

gives the same error.
Also a subsequent clf or cla command could not solve the problem.
Has anyone of you an idea what is going on here (or what I'm doing
wrong)? My matplotlib version is 0.71-1.

best regards
  Eugen Wintersberger

Eugen Wintersberger <eugen.wintersberger@...499...>