Vintage and modern Mandelbrot set in Go.

mandelbrot.go

package main

import "fmt"
import "math/cmplx"

func dot(bits uint8) string {
    bits = bits & 7 | (bits & 112) >> 1 | (bits & 8) << 3 | bits & 128
    return string(0x2800 + uint32(bits))
}

func mandelbrot(x float64, y float64, iteration int) uint8 {
    var c complex128 = complex(x, y)
    var r = c
    for i := 0; i < iteration; i ++ {
        r = r * r + c
        if cmplx.Abs(r) > 2 {
            return 0
        }
    }

    return 1
}

func main() {
  var R = 40

  for y := -R / 2; y < R / 2; y++ {
    for x := -R; x < R; x++ {
      if mandelbrot(-0.7 + 0.7 * float64(x * 2) / float64(R), 0.7 * float64(y  *4) / float64(R), 1000) > 0 {
        fmt.Print("*")
      } else {
        fmt.Print(" ")
      }
    }
    fmt.Println()
  }

  for y := -R / 2; y < R / 2; y++ {
    for x := -R; x < R; x++ {
      var r uint8 = 0
      for i := 0; i < 8; i++ {
        r |= mandelbrot(-0.7 + 0.7 * float64(x * 2 + ((i & 4) >> 2)) / float64(R), 0.7 * float64(y * 4 + (i & 3)) / float64(R), 1000) << uint8(i)
      }
      fmt.Print(dot(uint8(r)))
    }
    fmt.Println()
  }
}