Length based sigmoid selectivity function

Edit this page.   Source: R/selectivity_funcs.R

A sigmoid shaped selectivity function. Based on two parameters l25 and l50 which determine the length at which 25% and 50% of the stock is selected respectively. As the size-based model is weight based, and this selectivity function is length based, it is also necessary to supply the length-weight parameters a and b.

sigmoid_length(w, l25, l50, a, b)

Arguments

w

the size of the individual.
l25

the length which gives a selectivity of 25%.
l50

the length which gives a selectivity of 50%.
a

the multiplier of the length-weight function.
b

the exponent of the length-weight function.