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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