Naive implementation of visualizing a julia set with Kotlin

JuliaSet.kt

package de.halirutan.kotlin

import java.awt.Color
import java.awt.Image
import java.awt.image.BufferedImage
import javax.swing.ImageIcon
import javax.swing.JFrame
import javax.swing.JLabel
import javax.swing.JPanel


val log2 = Math.log(2.0)

data class Triple(private val a: Double, private val b: Double, private val c: Double) {
    fun toRGB() : Int {
        return Color.HSBtoRGB(a.toFloat(), b.toFloat(), c.toFloat())
    }
}

data class Complex(private val re: Double, private val im: Double) {
    operator fun plus(z: Complex) = Complex(re+z.re, im+z.im)
    operator fun times(z: Complex) = Complex(re*z.re-im*z.im, re*z.im+im*z.re)
    fun abs() = Math.sqrt(re*re+im+im)
    override fun toString() = "$re+I*$im"
}

fun iterator(juliaFunction: (Complex) -> Complex, zStart: Complex, maxIter: Int): Triple {
    var z = zStart
    for (i in 0..maxIter) {
        if (z.abs() > 2.0) {
            return Triple(0.0, 0.0, (i.toDouble())/maxIter.toDouble() + (log2/z.abs())/5.0)
        }
        z = juliaFunction(z)
    }
    return Triple(Math.cos(1 - (log2/z.abs())+Math.PI/2.0), 1.0, 1.0)
}

fun createJuliaImage(nx: Int, ny: Int, juliaFunction: (Complex) -> Complex) : Image {
    val data = Array(nx*ny, {
        val x = 2.0*(it % nx)/nx.toDouble() - 1.0
        val y = 2.0*(it / nx)/ny.toDouble() -1.0
        Complex(x,y)
    })

    val pixel = data.map({iterator(juliaFunction,it, 200).toRGB()})
    val img = BufferedImage(nx, ny, BufferedImage.TYPE_INT_RGB)
    img.setRGB(0, 0, nx, ny, pixel.toIntArray(), 0, nx)
    return img
}

fun main(args: Array<String>) {
    val nx = 2048
    val ny = 2048
    val f: (Complex) -> Complex = {z -> z*z+Complex(-0.8, 0.156)}
    val img = createJuliaImage(nx, ny, f)
    val scaledImg = img.getScaledInstance(nx/2, ny/2, Image.SCALE_SMOOTH)
    val frame = JFrame("Julia Image")
    val imgAsLabel = JLabel()
    imgAsLabel.icon = ImageIcon(scaledImg)
    frame.defaultCloseOperation = JFrame.EXIT_ON_CLOSE
    val panel = JPanel()
    panel.add(imgAsLabel)
    frame.contentPane.add(panel)
    frame.pack()
    frame.isVisible = true
}