docs: public static <A> double[] alphaPWM(A data, NumberArrayAdapter<?, A> adapter, final int nmom) {
      final int n = adapter.size(data);
      final double[] xmom = new double[nmom];
      double weight = 1. / n;
      for(int i = 0; i < n; i++) {
        final double val = adapter.getDouble(data, i);
        xmom[0] += weight * val;
        for(int j = 1; j < nmom; j++) {
          weight *= (n - i - j + 1) / (n - j + 1);
          xmom[j] += weight * val;
        }
      }
      return xmom;
    }