September 2017 Update

Task/Mandelbrot-set/Factor/mandelbrot-set.factor

@@ -0,0 +1,31 @@
+! with ("::") or without (":") generalizations:
+! : [a..b] ( steps a b -- a..b ) 2dup swap - 4 nrot 1 - / <range> ;
+::  [a..b] ( steps a b -- a..b ) a b b a - steps 1 - / <range> ;
+
+: >char ( n -- c )
+    dup -1 = [ drop 32 ] [ 26 mod CHAR: a + ] if ;
+
+! iterates z' = z^2 + c, Factor does complex numbers!
+: iter ( c z -- z' ) dup * + ;
+
+: unbound ( c -- ? ) absq 4 > ;
+
+:: mz ( c max i z -- n )
+  {
+    { [ i max >= ] [ -1 ] }
+    { [ z unbound ] [ i ] }
+    [ c max i 1 + c z iter mz ]
+  } cond ;
+
+: mandelzahl ( c max -- n ) 0 0 mz ;
+
+:: mandel ( w h max -- )
+    h -1. 1. [a..b] ! range over y
+    [   w -2. 1. [a..b] ! range over x
+        [ dupd swap rect> max mandelzahl >char ] map
+        >string print
+        drop ! old y
+    ] each
+    ;
+
+70 25 1000 mandel