MANDEL
!0000003B
: mandel
 gcls
begin 1 while
draw
repeat
key drop
;
-*-
v
XMAX
!00000027
( Maximum X value)
320 constant xmax
-*-
>
YMAX
!00000013
200 constant ymax
-*-
>
GCLS
!0000004A
: GCLS  cls <graphics> 4 vmode
        0 0 0 xmax 1- ymax 1- FILLBOX
;
-*-
>
DIS
!00000029
: dis

8 0 do
  i 0 palette
loop
;
-*-
>
DRAW
!00000289
\ Exploring the Mandelbrot set
: draw <float> <graphics>
  x gx f- xc f!                 \ Compute X corner
  xmax 0 do
    y gy f- yc f!               \ Compute Y corner
    gx xc f@ f+ xc f!           \ New X corner
    ymax 0 do                   \
      gy yc f@ f+ yc f!         \ New Y corner
      0. fdup                   \ Stk: 0 0
      64 cnt !
      64 1 do
        fover fover f* 2. f* yc f@ f+ yt f!
        fdup f* fswap fdup f* fover fover f+
        4. f> if fdrop fdrop i cnt ! leave endif
        fswap f- xc f@ f+ yt f@
      loop
      cnt @ j i pset
    loop  drop   ?term if key drop abort endif
  loop
;
-*-
v
X
!00000024
\ Real part start
-2. fconstant x
-*-
>
Y
!00000029
\ Imaginary part start
-2. fconstant y
-*-
>
SX
!00000026
\ Size of real part
4. fconstant sx
-*-
>
SY
!0000002B
\ Size of imagniary part
4. fconstant sy
-*-
>
GX
!00000038
\ Real pixel gap
<float> sx xmax i->f f/ fconstant gx
-*-
>
GY
!0000003D
\ Imaginary pixel gap
<float> sy ymax i->f f/ fconstant gy
-*-
>
XC
!00000032
\ real corner of pixel in progress
fvariable xc
-*-
>
YC
!00000037
\ imaginary corner of pixel in progress
fvariable yc
-*-
>
CNT
!00000037
\ count of iterations until z explodes
fvariable cnt
-*-
>
XT
!0000000E
fvariable xt
-*-
>
YT
!0000000E
fvariable yt
-*-
^
^