func PopulationVariance(input Float64Data) (pvar float64, err error) {
	v, err := _variance(input, 0)
	if err != nil {
		return math.NaN(), err
	}
	return v, nil
}
PopulationVariance finds the amount of variance within a population
package stats
import "math"
func _variance(input Float64Data, sample int) (variance float64, err error) {
	if input.Len() == 0 {
		return math.NaN(), EmptyInput
	}
	m, _ := Mean(input)
	for _, n := range input {
		variance += (float64(n) - m) * (float64(n) - m)
	}
	return variance / float64((input.Len() - (1 * sample))), nil
}
func Variance(input Float64Data) (sdev float64, err error) {
	return PopulationVariance(input)
}