Texas Instruments Titanium TI-89, User Manual

Page: 428 / 977

Differential Equation Graphing 425
Example Comparison of RK and Euler
Consider a logistic growth model
dP/dt = .001
ù
P
ù
(100 N P)
, with the initial condition
P(0) =
10
. Use the
BldData
instruction to compare the graphing points calculated by the RK and
Euler solution methods. Then plot those points along with a graph of the equation’s exact
solution.
Example
13. Return to the Graph screen, which
displays a curve for each pair of initial
conditions.
14. Press
…
to trace. Then press
3
¸
to
see the number of foxes (
xc
) and rabbits
(
yc
) at
t=3
.
Because
t0=0
and
tmax=10
, you can trace
in the range 0

t

10.
Note:
Use
C
and
D
to move the trace
cursor from one initial condition curve to
another.
1. Press
3
and set
Graph=DIFF
EQUATIONS
.