Dear matplotlib colleagues,

I am very new to matplotlib but I have been able to generate the plots I need; however, I am having trouble annotating a plot with an arrow. Could you help me with the syntax? Here is the code I am using:

ax.annotate('sol 9',xy=(xMinorLocs[9],0.5),xytext=(xMinorLocs[9],0.8),arrowprops=dict(width=1, frac=0.1, headwidth=5, facecolor='black')) 

when I do that, I get a 'ZeroDivisionError: float division'

As a test, I tried the command without the arrowprops:
ax.annotate('sol 9',xy=(xMinorLocs[9],0.5),xytext=(xMinorLocs[9],0.8))

and I didn't get any errors and the label was plotted (no arrow) at the right location. How can I get the arrow to show up?

Any help you can provide would be really appreciated.

Thanks and happy Holidays!

Fernando