void combine(final MomentStatistics b) {
		requireNonNull(b);

		final double m2 = _m2.value();
		final double m3 = _m3.value();

		final double pn = _n;
		final double n = _n + b._n;
		final double nn = n*n;

		final double d = b._m1.value() - _m1.value();
		final double dd = d*d;

		_n += b._n;

		_m1.add(d*b._n/n);

		_m2.add(b._m2).add(dd*pn*b._n/n);

		_m3.add(b._m3)
			.add(dd*d*(pn*b._n*(pn - b._n)/nn))
			.add(3.0*d*(pn*b._m2.value() - b._n*m2)/n);

		final double bnbn = (double)b._n*(double)b._n;

		_m4.add(b._m4)
			.add(dd*dd*(pn*b._n*(pn*pn - pn*b._n + bnbn)/(nn*n)))
			.add(6.0*dd*(pn*pn*b._m2.value() + bnbn*m2)/nn)
			.add(4.0*d*(pn*b._m3.value() - b._n*m3)/n);
	}
Combines the state of another {@code Moments} object into this one.

@see <a href="http://people.xiph.org/~tterribe/notes/homs.html">
     Computing Higher-Order Moments Online</a>
jenetics/src/main/java/io/jenetics/stat/MomentStatistics.java