The
program Sequen86 plots one recursive sequence with one initial
condition. The function is stored in variable y1, with x presenting
y1(n-1). The
initial condition is assumed to be y1(1).

This
program was originally posted on ticalc.org on April 28, 2001. Link:
https://www.ticalc.org/archives/files/fileinfo/186/18667.html

18
years, wow, how time flies.

**TI-86 Program Sequen86**

(354
bytes)

Func

FnOff

PlOff

ClLCD

DelVar(L1)

DelVar(L2)

Outpt(6,1,”Let
y1 = u”)

Outpt(7,1,”Let
x = n-1”)

InpSt
“y1 =”, Y

St>Eq(Y,y1)

Input
“Initial Cond: “,I

Input
“# of Steps: “,S

{I}
→ U

For(N,
dimL U+1, S+1, 1)

y1(U(N-1))
→ U(N)

End

seq(x,x,1,S+1)
→ L1

U
→ L2

0
→ xMin

S+1
→ xMax

min(U)
– 1 → yMin

max(U)
+ 1 → yMax

Plot1(1,L1,L2)

FnOff
1

Disp
“L1 = n”

Pause
“L2 = u”

DispG

Example:

u(n)
= u(n-1)/3 + 1/4

Initial
condition, u(1) = 1/5

Number
of Steps: 10

Set
up for Sequen86:

y1
= x/3 + 1/4

**The 2019 Version**

Here
is an alternate version, SEQGRAPH. Use
U for U(n-1) and N for n. The program allows the initial condition
for any value of N.

**TI-86 Program SEQGRAPH**

(277
bytes)

InpSt
“U1(U,N) = “,S1

St>Eq(S1,U1)

Input
“N Start = “,N

Input
“U0 = “,U

Input
“Steps: “,S

S
+ 1 → dimL xList

S
+ 1 → dimL yList

N
→ xList(1)

U
→ yList(1)

For(I,
2, S+1)

xList(I-1)
+ 1 → N

N
→ xList(I)

yList(I-1)
→ U

U1
→ yList(I)

End

FnOff

PlOff

PlOn
1

Plot1(1,xList,yList)

ZData

Example:

u(n)
= u(n-1)/3 + 1/4

Initial
condition, u(1) = 1/5

Number
of Steps: 10

Set
up for SEQGRAPH:

U1
= U/3 + 1/4

N
Start: 1

U0
= 1/5 (initial condition)

Eddie

All
original content copyright, © 2011-2019. Edward Shore.
Unauthorized use and/or unauthorized distribution for commercial
purposes without express and written permission from the author is
strictly prohibited. This blog entry may be distributed for
noncommercial purposes, provided that full credit is given to the
author.

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