open System.Numerics

​

let modSquared (c : Complex) = c.Real * c.Real + c.Imaginary * c.Imaginary

​

let maxIteration = 50000

​

let mandelbrot c =

    let rec loop z iterations =

        if (modSquared z >= 4.0) then iterations

        elif iterations = maxIteration then 0

        else loop ((z * z) + c) (iterations + 1)

    loop c 0

​

for y in seq{-1.2..0.15..1.2} do

    for x in seq{-2.0..0.07..0.9} do

        printf "%c" " .:-;!/>)|&IH%*#".[mandelbrot(Complex(x, y)) &&& 15]

    printfn ""

​