Texas Instruments TITANIUM TI-89 - Manual (Page 429)

Differential Equation Graphing 429
If you select ZoomSqr ( „
5 ), you can see that the phase-plane orbit is actually a circle.
However, ZoomSqr will change your Window variables.
6. In the Y= Editor, press:
@ 2 ‰and make sure
Axes = CUSTOM with y1 and y2 as the
axes.
Important: Fields=DIRFLD cannot plot a
time axis. An Invalid Axes error occurs if
Axes=TIME or if t is set as a CUSTOM axis.
7. In the Window Editor ( 8 $), set
the Window variables.
t0=0
tmax=10
tstep=.1
tplot=0 xmin= L 2
xmax=2
xscl=1
ymin=
L 2
ymax=2
yscl=1
ncurves=0
diftol=.001
fldres=14
dtime=0
8. Display the Graph screen ( 8 %).
x axis = y1 = y
y axis = y2 = y'