Math 145, Winter 99: Chaos Theory


Lab #7: Critical curves


We continue our work with 2D iterations.
A few critical curves of the MQ map family define an absorbing area.
Maple script for an MQ map
This is a text version of the Maple script which was used to draw Fig. 4-01. We have not included it here as you will draw your own with our Tcl script.
Critical curves of the MQ map family
Crit curves of MQ
Download this ASCII file and save it on your hard disk,
Open the Wish program, and select this script

Instructions for the curves program

On openning:
We draw the critical curves of rank -1 and of rank 0 with the default values of the map family parameters, a = 0.7, and b = -0.8 (the sliders show zero)
Sliders for map parameters a and b
These come into use after clicking the Clear button
Clear button:
This clears the screen, reads the two sliders, and draws the fundamental critical curve of rank -1
Puff button:
Thus puffer computes 500 iterates of the standard initial point, (-0.5, -0.5), then another 500 iterates, etc., with each press of the button
NextLC button:
This button draws the next critical curve segment
Snap a Pic button
This will create a printable file ("canvas.ps") on the hard drive in the folder which contains the program "Wish" (probably "Tcl/Tk Folder") which may be printed on a Postscript printer
Try variations of the map parameters following the figures in the text, Chs. 4, 5, and 6, and notice how the critical curves locate the attractor.
References for 2D maps:
  • Chaos in Discrete Dynamical Systems, Chs. 4,5,6.
  • All books by Mira

Revised 19 Feb 1999 by Ralph