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############################################################################
#
# File: mandel1.icn
#
# Subject: Program to display the Mandelbrot set
#
# 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 Mandelbrot set. 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 size, real_size, i, j, c1, c2, x, y, n, x1, y1, limit, extent
size := 300
extent := 4.0 / size
limit := 30
WOpen("label=mandel", "height=" || size, "width=" || size) |
stop("*** cannot open window")
every i := 1 to size do {
every j := 1 to size / 2 do {
c1 := -2 + i * extent
c2 := 2 - j * extent
x := c1
y := c2
every 1 to limit do { # see what the orbit is
x1 := x ^ 2 - y ^ 2 + c1
y1 := 2 * x * y + c2
if (x1 ^ 2 + y1 ^ 2) > 4 then break next
x := x1
y := y1
}
DrawPoint(i, j, i, size - j)
}
}
Event()
end
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