Last active
July 28, 2017 09:09
-
-
Save elmariachi111/205daab6d9f71537d8a36b13f3c7a5f5 to your computer and use it in GitHub Desktop.
Feigenbaum's bifurcation diagram in Go
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
package main | |
import ( | |
"image" | |
"os" | |
"image/png" | |
"image/color" | |
"image/draw" | |
"runtime" | |
) | |
func logistic(x float64, r float64, it int) float64 { | |
for i := 0; i < it; i++ { | |
x = r * x * (1 - x) | |
} | |
return x | |
} | |
func logr(im *image.RGBA, x float64, its int) { | |
var i,j int = 0,0 | |
var X,Y float64= (float64)(im.Bounds().Max.X), (float64)(im.Bounds().Max.Y) | |
steps := 1.2 / X | |
for r := 2.8 ; r < 4.0 ; r += steps { | |
res := logistic(x, r, its) | |
i = (int)((X * (r-2.8)/1.2) ) | |
j = (int)((Y - Y * res)) | |
k := im.RGBAAt(i,j) | |
if (k.A == 255) { | |
if (k.R > 1) { | |
k.R = k.R - 1 | |
k.G = k.G - 1 | |
k.B = k.B - 1 | |
} | |
} else { | |
k.R = 175 | |
k.G = 175 | |
k.B = 175 | |
k.A = 255 | |
} | |
im.Set(i, j, k) | |
} | |
} | |
func computeX(im *image.RGBA, stepSize float64, from float64, to float64, c chan bool) { | |
for its := 50 ; its < 150 ; its += 10 { | |
for x := from; x < to; x += stepSize { | |
logr(im, x, its) | |
} | |
} | |
c <- true | |
} | |
func main() { | |
im := image.NewRGBA(image.Rect(0,0,2550,1080)) | |
gr := color.RGBA{220,220,220,255} | |
draw.Draw(im, im.Bounds(), &image.Uniform{gr}, image.ZP, draw.Src) | |
var numCPU = runtime.NumCPU() | |
stepSize := (1.0-0.01) / 2550.0 | |
sliceSize := 1.0/(float64)(numCPU) | |
c := make(chan bool, numCPU) | |
for cpu := 0 ; cpu < numCPU; cpu++ { | |
from := (float64)(cpu) * sliceSize | |
to := (float64)(cpu+1) * sliceSize | |
go computeX(im, stepSize, from, to , c) | |
} | |
for cpu := 0; cpu < numCPU; cpu++ { | |
<-c // wait for one task to complete | |
} | |
imgFile, err := os.Create("feigenbaum.png") | |
if err != nil { | |
return | |
} | |
defer imgFile.Close() | |
png.Encode(imgFile, im) | |
} | |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
So I just started learning the very basics of Go and managed to render a bifurcation diagram and save it to png. There are many parameters that could be externalized (esp. interesting for zooming) but for the first attempt the results aren't too bad :)
go build