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/* Mandelbrot integer demo
* Released under the MIT License
*/
let
/* Basic types. */
type bool = int
type coord = int
type value = int
type array2d = array of value
type image2d = { nrows : coord, ncols : coord, data : array2d }
/* Image creation. */
function image_new (ncols : coord, nrows : coord) : image2d =
image2d { nrows = nrows, ncols = ncols,
data = array2d[nrows * ncols] of 0 }
function image_set (input : image2d, col : coord, row : coord,
value : value) =
(
input.data[row * input.ncols + col] := value
)
function mandelbrot () =
let
type fp = int
var X : int := 300
var Y : int := 300
var ima : image2d := image_new (X, Y)
var fixsize: int := 16834
function mul(a : fp, b : fp) : fp = (a*b)/fixsize
function frac(n : int, d : int) : fp = (n*fixsize)/d
var xcenter : fp := frac(0016, 10000)
var ycenter : fp := frac(8224, 10000)
var xmin : fp := xcenter - frac(5,100)
var ymin : fp := ycenter - frac(5,100)
var xmax : fp := xcenter + frac(5,100)
var ymax : fp := ycenter + frac(5,100)
var xs : fp := (xmax - xmin)/X
var ys : fp := (ymax - ymin)/Y
function iterations(x:int, y:int) : int =
let
var i : int := 0
var p : fp := xmin+x*xs
var q : fp := ymin+y*ys
var x0 : fp := 0
var y0 : fp := 0
var xn : fp := 0
var four : fp := frac(4,1)
var two : fp := frac(2,1)
in
while (mul(xn,xn)+mul(y0,y0) < four) & (i < 256) do
(
i := i + 1;
xn := mul((x0+y0),(x0-y0)) + p;
y0 := mul(two,mul(x0,y0)) + q;
x0 := xn
);
i
end
in
(for y := 0 to (Y-1) do
for x := 0 to (X-1) do
let
var i : int := iterations(x,y)
in
image_set (ima, x, y, i)
end);
end
in
print("Mandelbrot demo\n");
mandelbrot()
end
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