Function tune_by_scaling 

pub fn tune_by_scaling<L>(
    trial: &mut L,
    target_acceptance: OpenUnitIntervalNumber,
    count: &Count,
)
where
    L: Adjust,

Tune adjustable move sizes toward a target acceptance ratio.

Use Sweep::tune or ParallelSweep::tune when tuning local trial move sizes. tune_by_scaling is an internal implementation detail that you can use to tune custom trial moves.

Pass tune_by_scaling a target acceptance ratio and the move count obtained during a sampling period with the current trial move size. tune_by_scaling will scale the trial move size by the factor:

\frac{a + \gamma}{t + \gamma}

where $a$ is the current acceptance (from count), $t$ is the target and $\gamma = 1.5$.