Defining a differential equation graph, Setting differential equation graphing mode – Texas Instruments TI-86 User Manual

Page 144

132

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 132 of 20

Defining a Differential Equation Graph

Most steps for defining a differential equation graph are similar to the steps for defining a
function graph. This chapter assumes that you are familiar with Chapter 5: Function
Graphing and Chapter 6: Graph Tools. This chapter details aspects of differential equation
graphing that differ from function graphing.

Generally,

DifEq

graphing mode differs from other graphing modes in these ways.

♦

You must select the field format or accept the default before defining the equations
(page 133).

♦

If an equation is higher than first order, you must convert it to an equivalent system of
first-order differential equations, and then store the system in the equation editor
(page 140 and page 142).

♦

When

FldOff

field format is selected, you must set initial conditions for each equation in

the system (page 136).

♦

After you have selected the field format setting, you must select

AXES

from the

GRAPH

menu and enter axes information or accept the defaults (page 137).

Setting Differential Equation Graphing Mode

To display the mode screen, press - m. To graph differential equations, you must
select

DifEq

graphing mode before you set the format, enter equations, or edit window

variable values. The TI

-86 retains in memory separate format, equation, and window data

for each graphing mode.

Chapters 8 and 9 each begin
with an example; Chapter 10
has several differential
equation examples
throughout the chapter.