Mandelbrot in 6 lines

Here you can see the power of Forth in action.

\ A Mandelbrot set recursion in just 6 lines of Forth !

fvariable ci fvariable c fvariable zi fvariable z

: >2? z f@ fdup f* zi f@ fdup f* f+ 4.0e f> ;

: nextr z f@ fdup f* zi f@ fdup f* f- c f@ f+ ; : nexti z f@ zi f@ f* 2.0e f* ci f@ f+ ;

: pixel c f! ci f! 0e z f! 0e zi f! 150 50 do nextr nexti zi f! z f! >2? if i unloop exit then loop bl ;

: left-to-right -1.5e 80 0 do fover fover pixel emit 0.026e f+ loop fdrop ;

: mandelbrot ( --) -1e 40 0 do left-to-right cr 0.05e f+ loop fdrop ;

mandelbrot \ execute mandelbrot

(*) after the original work of Robert W. Brooks and Peter Matelski,1978 ( my version was adapted from the one of Charles Childers).