package util

import (
	"fmt"
	"math"
)

// Round a given number to the number of places indicated. roundOn indicates what fraction to round up on (ex: .5)
func Round(val float64, roundOn float64, places int) (newVal float64) {
	var round float64
	pow := math.Pow(10, float64(places))
	digit := pow * val
	_, div := math.Modf(digit)
	if div >= roundOn {
		round = math.Ceil(digit)
	} else {
		round = math.Floor(digit)
	}
	newVal = round / pow
	return
}

func WithinVariance(x, y, variance int) (bool, error) {
	v := math.Abs(float64(variance))
	d := math.Abs(float64(x) - float64(y))
	if d >= v {
		return false, fmt.Errorf("Variance of %v larger than %v", d, variance)
	}
	return true, nil
}