Improved error reporting.

[forth.jl.git] / examples / mandelbrot.4th

diff --git a/examples/mandelbrot.4th b/examples/mandelbrot.4th
index 5707acb..9759a39 100644 (file)
--- a/examples/mandelbrot.4th
+++ b/examples/mandelbrot.4th
@@ -1,7 +1,7 @@
 ( --- Complex arithmetic --- )
 
 ( Location of floating point. )
-: precision 10000 ;
+10000 value precision
 
 : sign dup abs / ;
 
@@ -32,28 +32,33 @@
 
 : csq 2dup c* ;
 
+
+: conj ( x y -- x -y )
+    negate
+;
+
 : cmagsq ( x1 y1 -- mag )
-    csq abs
+    2dup conj c* +
 ;
 
 ( --- Mandelbrot set calculations  --- )
 
 : iterate ( cr ci zr zi -- cr ci z'r z'i )
-    csq c+
+    2over 2swap csq c+
 ;
 
-: inSet? ( cr ci -- res )
-    DEBUGON
+100 value maxiter
 
+: inSet? ( cr ci -- res )
     0 0     ( z_0 = 0 )
     
     true    ( flag indicating set membership )
-    100 0 do
+    maxiter 0 do
         drop
 
         iterate
         2dup cmagsq
-        4 >scaled > if
+        4 0 >scaled > if
             false ( not in set )
             leave
         then
@@ -65,21 +70,42 @@
     -rot 2drop -rot 2drop
 ;
 
-: xsteps 100 ;
-: ysteps 50 ;
+100 value xsteps
+30 value ysteps
 
 ( Draw the Mandelbrot Set!)
-: mandel ( x1 y1 x2 y2 -- )
-
-    1 pick 4 pick -
-    2 pick 5 pick do
-        i 0 inSet? if
-            42 emit
-        else
-            '.' emit
-        then
+: mandeldraw ( x1 y1 x2 y2 -- )
+
+    cr
+
+    0 pick 3 pick - ysteps /
+    1 pick 4 pick do
+
+        2 pick 5 pick - xsteps /
+        3 pick 6 pick do
+
+            i j inSet? if
+                42 emit
+            else
+                space
+            then
+
+        dup +loop
+        drop
+
+        cr
+
     dup +loop
+    drop
 ;
 
 ( Clean up - hide non-standard multiplication def. )
 hide *
+
+( Default picture )
+: mandel
+        -2 0 >scaled -1 0 >scaled 0 5 >scaled 1 0 >scaled
+        mandeldraw
+;
+
+CR .( Enter 'mandel' to draw the Mandelbrot Set.)