pub fn fast_step(
t: f64,
checks: usize,
rmse_at: impl Fn(f64) -> f64,
) -> (f64, usize)Expand description
Step for an RMSE target: start from the formula Δ = k·t, then take
log–log secant steps on the measured error (rmse ∝ Δ^γ), aiming 1% under
the target, for at most checks trials. Returns the largest tried step
that met the target (or the last one, halved, when none did) and the
number of trials.