package com

import "math"

type Ema struct {
	Alpha float64
	Val   float64
}

func NewEMA(alpha float64) *Ema {
	return &Ema{Alpha: alpha}
}

func (e *Ema) Update(val float64) float64 {
	if math.IsNaN(val) || math.IsInf(val, 0) {
		return math.NaN()
	}
	if e.Val == 0 {
		e.Val = val
	} else {
		e.Val = e.Val*(1-e.Alpha) + val*e.Alpha
	}
	return e.Val
}

func (e *Ema) Reset() {
	e.Val = 0
}