User Guide

Chapter 17: Activities 312
After you execute the program above, you can recall and display the picture with the instruction
RecallPic 6.
Graphing Cobweb Attractors
Problem
Using
Web format, you can identify points with attracting and repelling behavior in sequence
graphing.
Procedure
1. Press z. Select Seq and the default mode settings. Press y .. Select Web format
and the default format settings.
2. Press o. Clear all functions and turn off all stat plots. Enter the sequence that corresponds to
the expression Y
= K X(1NX).
u(n)=Ku(nN1)(1Nu(nN1))
u(nMin)=.01
:For(K,1,3000)
:rand!N
Beginning of For group.
:If N1à3
:Then
:.5X!X
:.5Y!Y
:End
If/Then group
:If 1à3 <N and N2à3
:Then
:.5(.5+X)!X
:.5(1+Y)!Y
:End
If/Then group.
:If 2à3<N
:Then
:.5(1+X)!X
:.5Y!Y
:End
If/Then group.
:Pt-On(X,Y)
:End
:StorePic 6
Draw point.
End of For group.
Store picture.