Texas Instruments TITANIUM TI-89 User Manual page 428

Example Example Example Example
1. Press 3 and set
2. Define a system of equations for the 2nd-
order equation.
Rewrite the equation and make the
necessary substitutions.
3. In the Y= Editor (8 #), enter the
system of equations.
4. Enter the initial conditions:
and
yi1=0 yi2=1
is the time at which the initial
Note: t0
conditions occur. It is also the first t
evaluated for the graph. By default,
5. Press:
,
9
— or —
@ 8 Í and set
,
OFF Solution Method = RK
Fields = DIRFLD
For 2nd-order equations, you
Important:
must set
Fields=DIRFLD
Differential Equation Graphing
Graph=DIFF EQUATIONS
,
Axes = ON Labels =
, and
.
or
FLDOFF
.
y'' + y = 0
y'' = L y
y'' = y1
L
y2' = L y1
yi1 is the initial
condition for y(0).
. yi2 is the initial
t0=0
condition for y'(0).
.
428