Texas Instruments PLUS TI-89 User Manual
Page 194
Chapter 11: Differential Equation Graphing 177
11DIFFEQ.DOC TI-89/TI-92 Plus: Differential Equation (English) Susan Gullord Revised: 02/23/01 11:04 AM Printed: 02/23/01 2:15 PM Page 177 of 26
Steps
³
TI-89
Keystrokes
›
TI-92 Plus
Keystrokes
Display
6. Return to the Y= Editor and
enter an initial condition:
yi1=10
¥ #
¸ 1 0
¸
¥ #
¸ 1 0
¸
7. Return to the Graph screen.
Initial conditions entered in the
Y= Editor always occur at t0. The
graph begins at the initial condition
and plots to the right. Then it plots to
the left.
¥ %
¥ %
8. Return to the Y= Editor and
change
yi1
to enter two initial
conditions as a list:
yi1={10,20}
¥ # C
¸ 2 [
1 0 b 2 0 2 \
¸
¥ # C
¸ 2 [
1 0 b 2 0 2 \
¸
9. Return to the Graph screen.
¥ %
¥ %
10. To select an initial condition
interactively, press:
TI
-
89
:
2 Š
TI
-
92 Plus:
Š
When prompted, enter
t=40
and
y1=45
.
When selecting an initial condition
interactively, you can specify a value
for t other than the t0 value entered in
the Y= Editor or Window Editor.
Instead of entering t and y1 after
pressing TI
-
89:
2 Š
TI
-
92 Plus:
Š
, you can move the
cursor to a point on the screen and
then press
¸
.
You
can
use
…
to trace curves for
initial conditions specified in the Y=
Editor. However, you cannot trace the
curve for an initial condition selected
interactively.
2 Š
4 0 ¸
4 5 ¸
Š
4 0 ¸
4 5 ¸
The initial condition is
marked with a circle.