Texas Instruments PLUS TI-89 - Manual (Page 205)

188 Chapter 11: Differential Equation Graphing
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 188 of 26
To examine this harmonic oscillator in more detail, use a split screen
to graph the manner in which
y and y' change with respect to time (t) .
9. Press 3 and change the
mode settings on Page 2 as
shown. Then close the
MODE
dialog box, which redraws the
graph.
10. Press 2 a to switch to the
right side of the split screen.
11. Use † to select y1' and y2' .
The right side uses the same
equations as the left side.
However, no equations are
selected initially in the right
side.
12. Press:
ƒ 9
— or —
TI - 89: ¥ Í
TI - 92 Plus: ¥ F
Set Fields = FLDOFF .
13. In the Y= Editor, press:
TI - 89 : 2 ‰
TI - 92 Plus: ‰
and make sure Axes = TIME .
14. In the Window Editor, change
ymin and ymax as shown to the
right.
ymin= ë 2.
ymax=2.
15. Press ¥ % to display the
Graph screen for graph #2.
The left side shows the phase-
plane orbit. The right side
shows the solution curve and
its derivative.
16. To return to a full screen of
the original graph, press
2 a to switch to the left
side. Then press 3 and
change the
Split Screen setting.
Split Screen = FULL
Note: To display different
graphs in both parts of a
split screen, you must use
the 2-graph mode.
Important: Because
Fields=DIRFLD
cannot plot a
time axis, you must change
the Fields setting. FLDOFF
turns off all fields.
Note: When you enter 2-
graph mode, Window
variables for the right side
are set to their defaults.
y' y