A sigmoidal selectivity function with 50% selectivity at
weight sigmoidal_weight \(=w_{\text{sigmoid}}\) and width sigmoidal_sigma \(=\sigma\).
$$S(w) = \left(1 + \left(\frac{w}{w_{\text{sigmoid}}}\right)^{-\sigma}\right)^{-1}$$
sigmoid_weight(w, sigmoidal_weight, sigmoidal_sigma, ...)Vector of selectivities at the given sizes.
Vector of sizes.
The weight at which the knife-edge operates.
The width of the selection function.
Unused
gear_params() for setting the selectivity parameters.
Other selectivity functions:
double_sigmoid_length(),
knife_edge(),
sigmoid_length()