public static double sd(SlidingWindow left, SlidingWindow right) {
int n = left.maxSize + right.maxSize;
double sumOfSquares = (left.sumOfSquares() + right.sumOfSquares());
double sum = left.sum() + right.sum();
return Math.sqrt((n * (sumOfSquares) - (sum * sum)) / (n * (n - 1)));
}
public static double mean(SlidingWindow left, SlidingWindow right) {
return (left.mean() + right.mean()) / 2;
}