Texas Instruments TI-89, TI-92 - page 166

Chapter 9: Sequence Graphing 149
09SEQUEN.DOC TI-89/TI-92 Plus: Sequence Graphing (English) Susan Gullord Revised: 02/23/01 10:59 AM Printed: 02/23/01 2:14 PM Page 149 of 14
5. On the Y= Editor, set Axes = WEB and Build Web = AUTO.
6. On the Window Editor, change
the Window variables.
nmin=0. xmin=ë10.ymin=ë10.
nmax=10. xmax=10. ymax=10.
plotStrt=1. xscl=1. yscl=1.
plotStep=1.
7. Regraph the sequence.
The web plot shows how
quickly the sequence
diverges to large negative
values.
This example shows how the initial value can affect a sequence.
1. On the Y= Editor ( ¥#), use the same sequence defined in the
divergence example: u1(n) = 3.2u1(nì1) ì.8(u1(nì1))2. Set initial
value ui1 = 0.5.
2. Set Axes = TIME.
3. On the Window Editor
( ¥$), set the
Window variables.
nmin=1. xmin=0. ymin=0.
nmax=100. xmax=100. ymax=5.
plotStrt=1. xscl=10. yscl=1.
plotStep=1.
4. Graph the sequence
( ¥%
).
5. On the Y= Editor, set Axes = WEB and Build Web = AUTO.
6. On the Window Editor, change
the Window variables.
nmin=1. xmin=ë2.68 ymin=ë4.7
nmax=100. xmax=6.47 ymax=4.7
plotStrt=1. xscl=1. yscl=1.
plotStep=1.
7. Regraph the sequence.
8. Press …. Then use B to trace the web.
As you trace to larger values of nc, notice that xc and yc oscillate
between 2.05218 and 3.19782.
9. On the Window Editor, set
plotstrt=50. Then regraph the
sequence.
Example:
Oscillation
Note: Compare this graph
with the divergence
example. This is the same
sequence with a different
initial value.
Note: The web moves to an
orbit oscillating between two
stable points.
Note: By starting the web
plot at a later term, the
stable oscillation orbit is
shown more clearly.
u(n)
y=x
u(nì1)
u(n)
n
u(n)
y=x
u(nì1)
y=3.2xì.8xñ
y=3.2xì.8xñ