Texas Instruments TI-89 Manuale Utente

Differential Equation Graphing

413

Note:

You can use the

Define

command from the Home screen to define functions and

equations.

When entering equations in the Y= Editor, do not use

y(t)

formats to refer to results. For

example:

Only 1st-order equations can be entered in the Y= Editor. To graph 2nd- or higher-order
equations, you must enter them as a system of 1st-order equations.

Detailed information is available on setting initial conditions.

Selecting Differential Equations

Important:

Selecting y1' will graph the y1 solution curve, not the derivative y1', depending

on the axis setting.

Enter: y1' = .001y1

ù(100Ny1)

Not: y1' = .001y1(t)

ù(100Ny1(t))

Do not use implied multiplication between a
variable and parenthetical expression. If you
do, it is treated as a function call.

You can use

†

to select a differential

equation, but not its initial condition.