(11C) Rabbits VS Foxes Simulation

[Gamo]

This program was modify from the promotional ad for the
HP-25 Scientific Programmable calculator.

A simple ecological model of interacting populations consists of rabbits with an infinite food supply and foxes that prey on them.
The system can be approximated by a pair of nonlinear, first-order differential equations.

This program simulate the population between the rabbit and fox given the number of rabbits and the number of foxes.

Example:
α = 0.01 // STO 0 // Frequency (how often rabbits and foxes meet)
h = 0.02 // STO 1 // Step size
r = 300 // Rabbits
f = 150 // Foxes

In Run mode: Clear REG
,01 STO 0
,02 STO 1
300 [ENTER] 150 f [A]

Display keep going:
303,00156 // 303 are Rabbits and 156 are Foxes
305,00162
307,00169
309,00176
311,00183
312,00191
312,00199
.
.
.
Simulation keep going for observation........
Press any keys except [ON] to stop.
Press [R/S] to continue.

User can turn off the calculator and keep continue from where you stop the last time simply press [R/S] assuming that the storage registers haven't been change.

Program: Rabbits VS Foxes Populations

Code:


LBL A
STO 2
Rv
STO 3
FIX 5
LBL 0
RCL 2
ENTER
ENTER
RCL 3
RCL 0
x
x
STO 4
X<>Y
-
RCL 1
x
+
X<0 ?
0
STO 2
RCL 3
2
x
RCL 4
-
RCL 1
x
RCL 3
+
X<0 ?
0
STO 3
INT
RCL 2
INT
EEX
5
÷
+
PSE
PSE
GTO 0

Gamo