# Problem differentiating exponential function in Maxima

1. Jul 18, 2009

### bitrex

Hey everyone, I'm new to using the Maxima software and I'm having some trouble. When I enter the following formula to be evaluated:

diff(1-exp^(-t/R*C),t);

I get the following output:

$$\frac{log\left( exp\right) \,C}{{exp}^{\frac{t\,C}{R}}\,R}$$

This doesn't look right, even if I simplify the numerator. Am I doing something wrong?

2. Jul 18, 2009

### f95toli

No, it is correct.
At least if log(exp) really means ln(e^1)

I think you are confused by the fact that you've (presumably) forgotten to but parentheses around the RC factor, 1/R*C=C/R not 1/(R*C).

3. Jul 19, 2009

### bitrex

Yes, that's the problem. I swear parenthesis and order of operations are going to be the death of me; I once took a course in Lisp. I still have nightmares. From what I understand, Maxima is written in and programmed by using Lisp.