Modelling an ordinary differential equation

I am completely new to computer modelling and I am trying to model bacterial growth.
I found a simple example online which I have seen work on a mac. However, when I try to code it on my windows pc I get stuck at the point after I type r = integrate.odeint(f, y0, t, args=(k, alpha)) because an error message comes up saying:

Traceback (most recent call last):
File "<pyshell#6>", line 1, in <module>
r = integrate.odeint(f, y0, t, args=(k, alpha))
NameError: name 'f' is not defined

Please could anyone with a pc run this model and tell me where I am going wrong?
The example I am trying to model can be found here: http://lister.dulci.duhs.duke.edu/~clibu...odels.html

Thanks