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############################################################################
#
# File: orbit.icn
#
# Subject: Program to display quadratic orbit
#
# Author: Ralph E. Griswold
#
# Date: June 17, 1994
#
############################################################################
#
# This file is in the public domain.
#
############################################################################
#
# This is a barebones version of a display of the orbit of a quadratic
# equation. It has deliberately been left simple and free of options so
# that the basic idea is clear and so that it can be used as the basis of
# more capable versions.
#
# This program is based on material given in "Chaos, Fractals,
# and Dynamics", Robert L. Devaney, Addison-Wesley, 1990.
#
############################################################################
#
# Requires: Version 9 graphics
#
############################################################################
#
# Links: wopen
#
############################################################################
link wopen
procedure main()
local extent, c, i, j, m, x
extent := 360
WOpen("label=orbit", "height=" || extent, "width=" || extent) |
stop("*** cannot open window")
every i := -320 to 40 do {
x := 0.0
c := i / 160.0
m := 160 * (c + 2)
every j := 0 to extent do {
x := x ^ 2 + c
if j < 50 then next # wait for things to take hold
DrawPoint(m, 75 * (2 - x))
}
}
Event()
end
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