Julia set: Difference between revisions

The following code build a ppm file named julia.ppm. So there is no need of an external library to create the final image.

<lang julia>

function iter(z,c)

n = 0

while (n<256 && norm(z)<2) z = z^2+c ; n+=1 end

return n

end

coord(i,j,w,h,a,b) = 2*a*(i-1)/(w-1) - a + im * (2*b*(j-1)/(h-1) - b)

palette(n) = string(min(3n,255)," ", min(n,255)," ", 0," ");

julia(c) = (w,h,a,b,i,j) -> palette(iter(coord(i,j,w,h,a,b), c))

writeppm(f; width=600,height=300,a=2,b=1,file="julia.ppm") =

open(file, "w") do out

write(out, string("P3\n", width, " ", height, "\n255\n"))

writedlm(out, [f(width,height,a,b,i,j) for j = 1:height, i = 1:width], '\n')

end

</lang>

We can then produce a 800x600 ppm image of the Julia set associated to the parameter ''-0.786+0.147i'' as follows.

<pre>writeppm(julia(-0.786+0.147im))</pre>

The following code makes use of the library '''Images''' to build a png image.