func (ema EMASeries) GetSigma() float64 {
	return 2.0 / (float64(ema.GetPeriod()) + 1)
}
GetSigma returns the smoothing factor for the serise.
package chart
import "fmt"
const (
	DefaultEMAPeriod = 12
)
var (
	_ Series              = (*EMASeries)(nil)
	_ FirstValuesProvider = (*EMASeries)(nil)
	_ LastValuesProvider  = (*EMASeries)(nil)
)
type EMASeries struct {
	Name  string
	Style Style
	YAxis YAxisType
	Period      int
	InnerSeries ValuesProvider
	cache []float64
}
func (ema EMASeries) GetName() string {
	return ema.Name
}
func (ema EMASeries) GetStyle() Style {
	return ema.Style
}
func (ema EMASeries) GetYAxis() YAxisType {
	return ema.YAxis
}
func (ema EMASeries) GetPeriod() int {
	if ema.Period == 0 {
		return DefaultEMAPeriod
	}
	return ema.Period
}
func (ema EMASeries) Len() int {
	return ema.InnerSeries.Len()
}