# Function notation minus one exponent?

1. Oct 30, 2011

### bangthatdrum

Hi !

What does the notation mean exactly when a function has power minus one ?

For example i have seen the logistic function written as:

f(x) = f0[1 + exp(−βx)]^-1

2. Oct 30, 2011

### gb7nash

$$z^{-1} = \frac{1}{z}$$

For instance:

$$2^{-1} = \frac{1}{2}$$