Weight based sigmoidal selectivity function

A sigmoidal selectivity function with 50% selectivity at weight sigmoidal_weight \(=w_{\text{sigmoid}}\) and width sigmoidal_sigma \(=\sigma\). $$S(w) = \left(1 + \left(\frac{w}{w_{\text{sigmoid}}}\right)^{-\sigma}\right)^{-1}$$

Usage

sigmoid_weight(w, sigmoidal_weight, sigmoidal_sigma, ...)

Arguments

w

Vector of sizes.

sigmoidal_weight

The weight at which selectivity is 50%.

sigmoidal_sigma

The width of the selection function.

...

Unused

Value

Vector of selectivities at the given sizes.

Details

You would not usually call this function directly. Instead, set the sel_func column in gear_params() to "sigmoid_weight" and provide sigmoidal_weight and sigmoidal_sigma as additional columns. setFishing() will then call this function automatically when calculating the selectivity array.

See also

gear_params() for setting the selectivity parameters.

Other selectivity functions: double_sigmoid_length(), knife_edge(), sigmoid_length()

Examples

sigmoid_weight(w = c(1, 10, 100, 1000),
               sigmoidal_weight = 100, sigmoidal_sigma = 3)
#> [1] 9.99999e-07 9.99001e-04 5.00000e-01 9.99001e-01