variance function

double variance(List<double> x)

Implementation

double variance(List<double> x) {
  if (x.length < 2) return double.nan;
  final m = mean(x);
  var s = 0.0;
  for (final v in x) {
    final d = v - m;
    s += d * d;
  }
  return s / (x.length - 1);
}