Mandelbrot in Golang (as PNG) based on @benhoyt's mandel.awk

mandelbrot.go

package main

import (
	"image/color"
	"image/png"
	"image"
	"fmt"
	"os"
)

// based on https://github.com/benhoyt/goawk/blob/master/examples/mandel.awk

func main() {
	width := 150
	height := 50
	minX := -2.1
	maxX := 0.6
	minY := -1.2
	maxY := 1.2
	iters := 32.0

	img := image.NewNRGBA(image.Rect(0, 0, width, height))

	colors := []color.NRGBA{
		color.NRGBA{0xFF, 0xFF, 0xFF, 0xFF},
		color.NRGBA{0xFF, 0xEE, 0xDD, 0xFF},
		color.NRGBA{0xEE, 0xCC, 0xAA, 0xFF},
		color.NRGBA{0xDD, 0xBB, 0x88, 0xFF},
		color.NRGBA{0xCC, 0xAA, 0x77, 0xFF},
		color.NRGBA{0xBB, 0x88, 0x66, 0xFF},
		color.NRGBA{0x99, 0x66, 0x33, 0xFF},
		color.NRGBA{0x66, 0x44, 0x22, 0xFF},
		color.NRGBA{0x00, 0x00, 0x00, 0xFF},
	}

	incY := (maxY - minY) / float64(height)
	incX := (maxX - minX) / float64(width)

	y := minY
	for row := 0; row < height; row++ {
		x := minX
		for col := 0; col < width; col++ {
			zi := 0.0
			zr := zi

			i := 0.0
			for ; i < iters; i++ {
				oldZr := zr
				zr = zr * zr - zi * zi + x
				zi = 2 * oldZr * zi + y

				if zr * zr + zi * zi > 4 {
					break
				}
			}

			img.Set(col, row, colors[int((i*8) / iters)])

			x += incX
		}

		y += incY
	}

	fd, err := os.Create("mandelbrot.png")
	if err != nil {
		panic(err)
	}

	if err := png.Encode(fd, img); err != nil {
		fd.Close()
		panic(err)
	}

	if err := fd.Close(); err != nil {
		panic(err)
	}

	fmt.Println("File mandelbrot.png written")
}