1 files changed, 157 insertions, 0 deletions
diff --git a/generate.go b/generate.go
new file mode 100644
index 0000000..8701e20
--- /dev/null
+++ b/generate.go
@@ -0,0 +1,157 @@
+package main
+
+import (
+	"fmt"
+	"gopkg.in/cheggaaa/pb.v1"
+	"math"
+	"math/rand"
+	"os"
+)
+
+const (
+	sigma = 200.0
+	f_0   = 0.1
+	G     = 4.302e-3
+	R_s   = 1e4
+)
+
+type star struct {
+	x float64
+	y float64
+	z float64
+}
+
+func rho(x, y, z float64) float64 {
+	var r float64 = math.Sqrt((x * x) + (y * y) + (z * z))
+	var a float64 = (1) / (math.Sqrt(2*math.Pi) * sigma)
+	var b float64 = math.Exp(-(phi(r) / float64(sigma*sigma)))
+	//aphi := phi(r)
+	//asigma := float64(sigma * sigma)
+	//fmt.Println(aphi, asigma, math.Exp( - (aphi / asigma)))
+	return a * b
+}
+
+func phi(x float64) float64 {
+	if x == 0 {
+		return (-4 * math.Pi * f_0 * G * (R_s * R_s))
+	} else {
+		var a float64 = -(4 * math.Pi * G * f_0 * (R_s * R_s * R_s) / x)
+		var b float64 = math.Log(1.0 + (x / R_s))
+		return (a * b)
+	}
+}
+
+func genStar(f *os.File) (bool, star) {
+	var length float64 = 1.5e7
+
+	var rangeMin float64 = -length
+	var rangeMax float64 = length
+
+	var randMin float64 = rho(0, 0, 0)
+	var randMax float64 = rho(length, length, length)
+
+	//(max - min) * rand.Float64()) + min
+	var x float64 = ((rangeMax - rangeMin) * rand.Float64()) + rangeMin
+	var y float64 = ((rangeMax - rangeMin) * rand.Float64()) + rangeMin
+	var z float64 = ((rangeMax - rangeMin) * rand.Float64()) + rangeMin
+
+	var randVal float64 = (randMax-randMin)*rand.Float64() + randMin
+
+	var rhoVal float64 = rho(x, y, z)
+
+	//fmt.Printf("x: %-20f y: %-20f z: %-20f randVal: %-20f rhoVal: %-20f\n", x, y, z, randVal, rhoVal)
+
+	if randVal < rhoVal {
+		var starString string = fmt.Sprintf("%f, %f, %f\n", x, y, z)
+		_, err := f.WriteString(starString)
+		if err != nil {
+			panic(err)
+		}
+		f.Sync()
+
+		//fmt.Printf("x: %-20f y: %-20f z: %-20f randVal: %-20f rhoVal: %-20f\n", x, y, z, randVal, rhoVal)
+
+		newStar := star{
+			x: x,
+			y: y,
+			z: z,
+		}
+
+		// return that a star was generated
+		return true, newStar
+	}
+
+	// return that no star was generated
+	return false, star{
+		x: 0,
+		y: 0,
+		z: 0,
+	}
+}
+
+func generateGoMethods(starCount int, f *os.File, channel chan star) {
+	var generatedStars int = 0
+
+	// for the amount of stars
+	for generatedStars < starCount {
+
+		// try to generate a new star
+		result, star := genStar(f)
+		if result == true {
+			generatedStars += 1
+			channel <- star
+		}
+	}
+}
+
+func main() {
+	// define some arguments
+	var stars int = 1e6
+	var threads int = 1
+	var threadStarCount int = stars / threads
+
+	// create a channel with a buffer of 10
+	channel := make(chan star, 10)
+
+	// create a file that stores the data
+	hostname, _ := os.Hostname()
+	pid := os.Getpid()
+	f, err := os.Create(fmt.Sprintf("%s_%d.csv", hostname, pid))
+	if err != nil {
+		panic(err)
+	}
+
+	// use 8 threads
+	// each thread should generate stars / 8 stars
+	for i := 0; i < threads; i++ {
+		fmt.Printf("Creating a happy worker! He/She is trying to generate %d stars!", threadStarCount)
+		// generate a go-method creating threadStarCound stars
+		go generateGoMethods(threadStarCount, f, channel)
+		fmt.Printf(" He/She just started working!\n")
+	}
+
+	// start the missing threads threads
+	var missingStars int = stars - (threadStarCount * threads)
+	fmt.Printf("A special worker was assigned to generate the last %d stars.\n", missingStars)
+	go generateGoMethods(missingStars, f, channel)
+
+	var starSlice []star
+
+	// Initialize a new progress bar
+	bar := pb.New(stars).Prefix("Stars: ")
+	bar.Start()
+
+	// get the stars
+	for i := 0; i < stars; i++ {
+		var newStar = <-channel
+		bar.Increment()
+		starSlice = append(starSlice, newStar)
+	}
+
+	bar.Finish()
+
+	// print all elements in the starslice
+	for _, element := range starSlice {
+		fmt.Println(element)
+	}
+}