Using Web Plots To Illustrate Convergence - Texas Instruments TI-84 PLUS - Graphing Calculator Manual Book

A potential convergence point occurs whenever a sequence intersects the
Note:
line. However, the sequence may or may not actually converge at that point, depending on the
sequence's initial value.
Drawing the Web
To activate the trace cursor, press r. The screen displays the sequence and the current
and Y values (X represents
step by step, starting at
1. It starts on the x-axis at the initial value
2. It moves vertically (up or down) to the sequence.
3. It moves horizontally to the
4. It repeats this vertical and horizontal movement as you continue to press ~.

Using Web Plots to Illustrate Convergence

Example: Convergence
1. Press o in
mode to display the sequence Y= editor. Make sure the graph style is set to
Seq
í (dot), and then define
2. Press y . Í to set
3. Press p and set the variables as shown below.
nMin=1
nMax=25
PlotStart=1
PlotStep=1
4. Press s to graph the sequence.
5. Press y . and select the
and Y represents
u(n N 1)
. In Web format, the trace cursor follows this course.
nMin
u(nMin)
reference line.
y=x
, and
u(n) u(nMin)
nMin
axes format.
Time
Xmin=0
Xmax=25
Xscl=1
axes setting.
Web
). Press ~ repeatedly to draw the web
u(n)
(when ).
PlotStart=1
as u(n) = -.8u(n-1) + 3.6.
Ymin= L 10
Ymax=10
Yscl=1
Chapter 6: Sequence Graphing
reference
y=x
, X,
n
110