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 3and change the
mode settings on Page 2 as
shown. Then close the MODE
dialog box, which redraws the
graph.
10.Press 2a
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=ë2.
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
2a
to switch to the left
side. Then press 3and
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