Texas Instruments TI-89 Manuale Utente
![Texas Instruments](https://files.manualsbrain.com/attachments/b46f99d826b2b0e0e5f558c5fb6483942eb9216b/common/fit/150/50/c15ea36eb1fb1cce99a3b94668675bfc78ce832d8d727d9a7bb51a125510/brand_logo.gif)
Differential Equation Graphing
436
Predator-Prey Model
Predator-Prey Model
Predator-Prey Model
Predator-Prey Model
Use the two coupled 1st-order differential equations:
y1' = Ly1 + 0.1y1 ùy2 and y2' = 3y2 Ny1 ùy2
where:
y1 = Population of foxes
yi1 = Initial population of foxes (2)
y2 = Population of rabbits
yi2 = Initial population of rabbits (5)
1. Use
3 to set
Graph = DIFF
EQUATIONS
.
2. In the Y= Editor (
8 #), define the
differential equations and enter the
initial conditions.
initial conditions.
Note:
To speed up graphing times, clear
any other equations in the Y= Editor. With
FLDOFF
, all equations are evaluated even
if they are not selected.
3. Press:
,
9
— or —
@
8 Í Set
Axes = ON
,
Labels = ON
,
Solution Method = RK
, and
Fields = FLDOFF
.