Use float64 instead of big.Rat.

It's actually just fine to use float64.

1 files changed, 25 insertions, 41 deletions

diff --git a/mandelbrot.go b/mandelbrot.go
index 5876383..482850a 100644
--- a/mandelbrot.go
+++ b/mandelbrot.go
@@ -2,60 +2,44 @@ package main
 
 import (
 	"fmt"
-	"math/big"
-	"time"
 )
 
-var rat4 = big.NewRat(4, 1)
-
-func mandelbrot(x0, y0 *big.Rat) int {
-	x := new(big.Rat)
-	y := new(big.Rat)
-	x2 := new(big.Rat)
-	y2 := new(big.Rat)
-	temp := new(big.Rat)
-	i := 0
-	for ; temp.Add(x2, y2).Cmp(rat4) <= 0; i++ {
-		y.Add(y, y).Mul(y, x).Add(y, y0)
-		x.Sub(x2, y2).Add(x, x0)
-		x2.Mul(x, x)
-		y2.Mul(y, y)
+func mandelbrot(x0, y0 float64) int {
+	var x, y, x2, y2 float64
+	for i := 0; i < 1000; i++ {
+		if x2+y2 > 4 {
+			return (i-1)%6 + 1
+		}
+		y = (x+x)*y + y0
+		x = x2 - y2 + x0
+		x2 = x * x
+		y2 = y * y
 	}
-	return (i-1)%6 + 1
+	return 0
 }
 
-func printMandelbrot(xMin, xRange, yMin, yRange *big.Rat) error {
+func main() {
 	const (
+		xMin   = -2.
+		xRange = 2.47
+		yMin   = -1.12
+		yRange = 2.24
+
 		width  = 80
 		height = 25
+
+		xStep = xRange / float64(width)
+		yStep = yRange / float64(height)
 	)
 
-	grid := make([]int, width*height)
-	xStep := new(big.Rat).Quo(xRange, big.NewRat(int64(width), 1))
-	yStep := new(big.Rat).Quo(yRange, big.NewRat(int64(height), 1))
-	y := new(big.Rat)
-	x := new(big.Rat)
-	y.Set(yMin)
-	for i := 0; i < height; i++ {
-		x.Set(xMin)
-		for j := 0; j < width; j++ {
-			go func(i, j int, x, y *big.Rat) {
-				grid[i*width+j] = mandelbrot(x, y)
-			}(i, j, new(big.Rat).Set(x), new(big.Rat).Set(y))
-			x.Add(x, xStep)
-		}
-		y.Add(y, yStep)
-	}
-	time.Sleep(time.Minute)
+	y := yMin
 	for i := 0; i < height; i++ {
+		x := xMin
 		for j := 0; j < width; j++ {
-			fmt.Printf("\033[%dm ", 40+grid[i*width+j])
+			fmt.Printf("\033[4%dm ", mandelbrot(x, y))
+			x += xStep
 		}
 		fmt.Println("\033[49m")
+		y += yStep
 	}
-	return nil
-}
-
-func main() {
-	printMandelbrot(big.NewRat(-3, 2), big.NewRat(247, 100), big.NewRat(-112, 100), big.NewRat(224, 100))
 }