Functions with parameters?

*To*: mathgroup at smc.vnet.net*Subject*: [mg22214] Functions with parameters?*From*: tautenhahn at fichtelgebirge.org (Nikolas Tautenhahn)*Date*: Fri, 18 Feb 2000 02:34:51 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Hi there! I have Mathematica 4 and I want to discuss a simple function with a parameter; The problem, however, is that I neither found some help in the online help of Mathematica nor in the book (which is about Mathematica 3) by Michael Kofler. I don't know if it is possible to do everything I want to do with Mathematica and that's why I'm asking here. The function I want to discuss is f(x)=ln(x/(x-a) with a>0 ok, in Mathematica you type f[x_]=Log[x/(x-a)]. what I want to do is: * where is this function defined (I don't know if this is the right English word; for example 1/x is *not* defined for x=0; i hope you understand what I mean); * derivatives etc. --> no problem, but again: where is f'(x) defined? * Plot the function for several values of a Thanks in advance from a newbie Nikolas Tautenhahn