Texas Instruments 83CML/ILI/U Guidebook - Page 129

Graphing Web Plots

Page 129 highlights

Graphing Web Plots Graphing a Web Plot To select Web axes format, press y [FORMAT] ~ Í. A web plot graphs u(n) versus u(nN1), which you can use to study long-term behavior (convergence, divergence, or oscillation) of a recursive sequence. You can see how the sequence may change behavior as its initial value changes. Valid Functions for Web Plots When Web axes format is selected, a sequence will not graph properly or will generate an error. • It must be recursive with only one recursion level (u(nN1) but not u(nN2)). • It cannot reference n directly. • It cannot reference any defined sequence except itself. Displaying the Graph Screen In Web format, press s to display the graph screen. The TI-83: • Draws a y=x reference line in AxesOn format. • Plots the selected sequences with u(nN1) as the independent variable. Note: A potential convergence point occurs whenever a sequence intersects the y=x reference 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 n, X, and Y values (X represents u(nN1) and Y represents u(n)). Press ~ repeatedly to draw the web step by step, starting at nMin. In Web format, the trace cursor follows this course. 1. It starts on the x-axis at the initial value u(nMin) (when PlotStart=1). 2. It moves vertically (up or down) to the sequence. 3. It moves horizontally to the y=x reference line. 4. It repeats this vertical and horizontal movement as you continue to press ~. Sequence Graphing 6-11

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Sequence Graphing
6-11
To select
Web
axes format, press
y
[
FORMAT
]
~
Í
. A
web plot graphs
u(
n
)
versus
u(
n
N
1)
, which you can use to
study long-term behavior (convergence, divergence, or
oscillation) of a recursive sequence. You can see how the
sequence may change behavior as its initial value changes.
When
Web
axes format is selected, a sequence will not
graph properly or will generate an error.
It must be recursive with only one recursion level
(
u(
n
N
1)
but not
u(
n
N
2)
).
It cannot reference
n
directly.
It cannot reference any defined sequence except itself.
In
Web
format, press
s
to display the graph screen.
The TI
-
83:
Draws a
y=x
reference line in
AxesOn
format.
Plots the selected sequences with
u(
n
N
1)
as the
independent variable.
Note:
A potential convergence point occurs whenever a sequence
intersects the y=x reference line. However, the sequence may or may
not actually converge at that point, depending on the sequence’s initial
value.
To activate the trace cursor, press
r
. The screen
displays the sequence and the current
n
,
X
, and
Y
values (
X
represents
u(
n
N
1)
and
Y
represents
u(
n
)
). Press
~
repeatedly to draw the web step by step, starting at
n
Min
.
In
Web
format, the trace cursor follows this course.
1.
It starts on the x-axis at the initial value
u(
n
Min)
(when
PlotStart=1
).
2.
It moves vertically (up or down) to the sequence.
3.
It moves horizontally to the
y=x
reference line.
4.
It repeats this vertical and horizontal movement as you
continue to press
~
.
Graphing Web Plots
Graphing a Web
Plot
Valid Functions
for Web Plots
Displaying the
Graph Screen
Drawing the Web