The optimal size of knots is chosen by a rule of thumb adapted from
Rose (2015).

bw_bern(udata)

## Arguments

## Value

optimal order of the Bernstein polynimals.

## Details

The formula is
$$max(1, round(n^(1/3) * exp(abs(rho)^(1/n)) * (abs(rho) + 0.1))),$$
where \(\rho\) is the empirical Spearman's rho of the data.