Texas Instruments TITANIUM TI-89 User Manual
Page 432

Differential Equation Graphing
432
Example
Example
Example
Example
1. Press
3 and set
Graph=DIFF EQUATIONS
.
2. Define a system of equations for the 3rd-
order equation.
Rewrite the equation and make the
necessary substitutions.
y''' + 2y'' + 2y' + y =
sin(x)
y''' = sin(x)
N
2y''
N
2y'
N
y
y''' = sin(t)
N
2y''
N
2y'
N
y
y''' = sin(t)
N
2y3
N
2y2
N
y1
y3' = sin(t)
N
2y3
N
2y2
N
y1
3. In the Y= Editor (
8 #), enter the
system of equations.
4. Enter the initial conditions:
yi1=0
,
yi2=1
, and
yi3=1
Note:
t0
is the time at which the initial
conditions occur. By default,
t0=0
.
5. Be sure that only
y1'
is selected. Use
†
to deselect any other equations.
Important: The
solution to the y1'
equation is the
solution to the 3rd-
order equation.