# predator prey

We assume we have two species, herbivores with population x,

and predators with propulation y. We assume that x grows

exponentially in the absence of predators, and that y decays

exponentially in the absence of prey. Consider, say, the system

x' = x - xy/2, y' = -y + xy/2. (*)

We call this the predator-prey model or the Lotka-Volterra model.

The following Sage commands implement this.

- File
- Author : David Joyner
- School level: high school
- Keywords: cryptography
- Language: English
- File format: Sage script (sage)
- License: unknown