Texas Instruments TI-89 Manual Book page 165

Example:
Convergence
Tip: During a trace, you can
move the cursor to a
specified n value by typing
the value and pressing
¸ .
Tip: When the nc value
changes, the cursor is on
the sequence. The next time
you press B , nc stays the
same but the cursor is now
on the y=x reference line.
Example:
Divergence
148 Chapter 9: Sequence Graphing
1. On the Y= Editor ( ¥ # ), define
initial value
ui1 = ë 4
2. Set .
Axes = TIME
3. On the Window Editor
( ¥ $ ), set the Window
variables.
4. Graph the sequence
( ¥ %).
By default, a sequence uses
the display style.
Square
5. On the Y= Editor, set
6. On the Window Editor, change
the Window variables.
7. Regraph the sequence.
Web plots are always shown
as lines, regardless of the
selected display style.
8. Press .... As you press B, the trace cursor follows the web. The
screen displays the cursor coordinates
and represent
yc u(nì 1)
As you trace to larger values of
the convergence point.
1. On the Y= Editor ( ¥ # ), define
Set initial value
ui1 = 4.45
2. Set Axes = TIME .
3. On the Window Editor
( ¥ $ ), set the
Window variables.
4. Graph the sequence
( ¥ % ).
Because the sequence
quickly diverges to large
negative values, only a few
points are plotted.
u1(n) = ë.8u1(nì 1) + 3.6
.
nmin=1.
nmax=25.
plotstrt=1.
plotstep=1.
u(n)
and
Axes = WEB Build Web = AUTO
nmin=1.
nmax=25.
plotStrt=1.
plotStep=1.
y=ë.8x + 3.6
y=x
nc ,
and , respectively).
u(n)
, you can see
nc
u1(n) = 3.2u1(nì 1) ì.8(u1(nì 1))
.
nmin=0.
nmax=10.
plotStrt=1.
plotStep=1.
u(n)
. Set
ë
xmin=0. ymin= 10.
xmax=25. ymax=10.
xscl=1. yscl=1.
n
.
ë ë
xmin= 10. ymin= 10.
xmax=10. ymax=10.
xscl=1. yscl=1.
u(n)
ì
u(n 1)
xc , and yc (where xc
and approach
xc yc
2
ë
xmin=0. ymin= 75.
xmax=10. ymax=10.
xscl=1. yscl=1.
n
.