simple multithreaded pythagorean triple finder.

pth-triples.go

package main

import (
	"fmt"
	"runtime"
)

func issqr(t int) int {
	for i := 0; true; i++ {
		if(i*i == t) {
			return i
		}else if(i*i > t){
			return -1
		}
	}
	return -1
}

func filt_triples(in chan [2]int, out chan [3]int) {
	for i := range in {
		temp := issqr(i[0]*i[0] + i[1]*i[1])
		if(temp != -1) {
			out <- [3]int{i[0], i[1], temp}
		}
	}
}

func sendvals(out chan [2]int) {
	cur := [2]int{1, 1}
	for {
		out <- cur
		if cur[0] >= cur[1] {
			cur[0] = 1
			cur[1]++
		} else {
			cur[0]++
		}
	}
}

func main() {
	nthreads := runtime.NumCPU()
	var ngr int
	if nthreads < 2 {
		ngr = 1
	} else {
		ngr = nthreads - 2
	}
	vals := make(chan [2]int, 0x100)
	triples := make(chan [3]int, 0x100)
	go sendvals(vals)
	for i := 0; i < ngr; i++ {
		go filt_triples(vals, triples)
	}
	for i := range triples {
		fmt.Println(i[0], i[1], i[2])
	}
}