Chapter 6: Sequence Graphing
104
In this editor, you can display and enter sequences for
u(
n
)
,
v(
n
)
, and
w(
n
)
. Also, you can edit the
value for
n
Min
, which is the sequence window variable that defines the minimum
n
value to
evaluate.
The sequence Y= editor displays the
n
Min
value because of its relevance to
u(
n
Min)
,
v(
n
Min)
, and
w(
n
Min)
, which are the initial values for the sequence equations
u(
n
)
,
v(
n
)
, and
w(
n
)
, respectively.
n
Min
in the
Y= editor is the same as
n
Min
in the window editor. If you enter a new value for
n
Min
in
one editor, the new value for
n
Min
is updated in both editors.
Note:
Use
u(
n
Min)
,
v(
n
Min)
, or
w(
n
Min)
only with a recursive sequence, which requires an initial
value.
Selecting Graph Styles
The icons to the left of
u(
n
)
,
v(
n
)
, and
w(
n
)
represent the graph style of each sequence (Chapter 3).
The default in Seq mode is
í
(dot), which shows discrete values. Dot,
ç
(line), and
è
(thick) styles
are available for sequence graphing. Graph styles are ignored in Web format.
Selecting and Deselecting Sequence Functions
The TI-84 Plus graphs only the selected sequence functions. In the Y= editor, a sequence function
is selected when the
=
signs of both
u(
n
)=
and
u(
n
Min)=
are highlighted.
To change the selection status of a sequence function, move the cursor onto the
=
sign of the
function name, and then press
Í
. The status is changed for both the sequence function
u(
n
)
and its initial value
u(
n
Min)
.
Defining and Editing a Sequence Function
To define or edit a sequence function, follow the steps in Chapter 3 for defining a function. The
independent variable in a sequence is
n
.
In Seq graphing mode, you can enter the sequence variable in either of two ways.
•
Press
„
.
•
Press
y N
[N]
.
You can enter the function name from the keyboard (
y
[u],
y
[v],
y
[w]).
Generally, sequences are either nonrecursive or recursive. Sequences are evaluated only at
consecutive integer values.
n
is always a series of consecutive integers, starting at zero or any
positive integer.