round implementation in go

rint.go

package main

import "fmt"
import "math"

// see http://www.gnu.org/software/libc/manual/html_node/Rounding.html
func rint(x float64) float64 {
	v, frac := math.Modf(x)
	if x > 0.0 {
		if frac > 0.5 || (frac == 0.5 && uint64(v)%2 != 0) {
			v += 1.0
		}
	} else {
		if frac < -0.5 || (frac == -0.5 && uint64(v)%2 != 0) {
			v -= 1.0
		}
	}

	return v
}

func main() {
	fmt.Println("Hello, playground")

	fmt.Printf("%f\n", rint(1.5))
	fmt.Printf("%f\n", rint(2.5))
}