Calculator User Manual
144
Chapter 10: Differential Equation Graphing
10DIFFEQ.DOC TI-86, Chap 10, US English Bob Fedorisko Revised: 02/13/01 2:28 PM Printed: 02/13/01 3:02 PM Page 144 of 2010DIFFEQ.DOC TI-86, Chap 10, US English Bob Fedorisko Revised: 02/13/01 2:28 PM Printed: 02/13/01 3:02 PM Page 144 of 2010DIFFEQ.DOC TI-86, Chap 10, US English Bob Fedorisko Revised: 02/13/01 2:28 PM Printed: 02/13/01 3:02 PM Page 144 of 20
Solving a Differential Equation for a Specified Value
On the home screen in
DifEq
graphing mode, you can solve a
differential equation stored to a specified independent variable
value or expression. The syntax is:
Q'
n
(
value
)
.
♦
The equation must be stored to a
DifEq
equation variable
(
Q'1
through
Q'9
).
♦
The initial conditions must be defined.
♦
The result sometimes varies, depending on the axes settings.
Using Graph Tools in DifEq Graphing Mode
The Free-Moving Cursor
The free-moving cursor works in
DifEq
mode as it does in
Func
graphing. The cursor
coordinate values for
x
and
y
are displayed, and the variables are updated.
Tracing a Differential Equation
To begin a trace, select
TRACE
from the
GRAPH
menu (
6
/
)
). The trace cursor
appears on the first equation at or near
tPlot
(or
tMin
, if
t
is an axis).
The trace coordinates displayed at the bottom of the screen reflect the axes settings. For
example, if
x=t
and
y=Q1
, then
t
and
Q1
are displayed. If
t
is not an axis, three trace values
are displayed. If
t
is an axis, only
t
and the variable designated as the y-axis are displayed.
The trace cursor moves in increments or decrements of
tStep
. As you trace an equation, the
coordinates are updated and displayed. If the cursor moves off the screen, the coordinate
values displayed at the bottom of the screen continue to change appropriately.
To paste
'
to the home
screen, you can select it from
the
CHAR
MISC
menu or fro
m
the
CATALOG
.
Due to TI
-
86 system
requirements, you must
express
Q1(3)
as
Q'1(3)
on
the calculator.
QuickZoom is available in
DifEq
graphing; panning is
not (Chapter 6).