gistfile1.go

package main

import "fmt"
import "rand"
import "math"
import "flag"

func main() {
    var hit int64
    var total int64
    var entropy int64
    var verbose bool

    flag.Int64Var(&entropy, "entropy", 10000, "define entropy")
    flag.BoolVar(&verbose, "verbose", false, "verbose mode")
    flag.Parse()

    if verbose {
        fmt.Printf("Gathering entropy, please wait...\n")
    }

    for total = 0; total < entropy; total++ {
        var x float = rand.Float()
        var y float = rand.Float()

        if math.Pow(float64(x), 2) + math.Pow(float64(y), 2) <= 1 {
            hit += 1;
        }
        if verbose {
            fmt.Printf("\r%.3f%% %d (%d) / %d", (float(total) / float(entropy)) * 100.0, total, hit, entropy)
        }
    }

    var pi float64 = (float64(hit) / float64(total)) * 4;

    if verbose {
        fmt.Printf("\napprox. value of pi: %v\n", pi)
    }else {
        fmt.Printf("%v\n", pi)
    }
}