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 uses the
length-weight parameters a
and b
to convert between length and weight.
Arguments
- w
Vector of sizes.
- l25
the length which gives a selectivity of 25%.
- l50
the length which gives a selectivity of 50%.
- species_params
A list with the species params for the current species. Used to get at the length-weight parameters
a
andb
.- ...
Unused
See also
Other selectivity functions:
double_sigmoid_length()
,
knife_edge()
,
sigmoid_weight()