logist: logist Logistic selectivity function

In haddonm/datalowSA: A Package to Faciliate Application of Data poor Stock Assessments

logist Logistic selectivity function

Description

logist calcualtes a Logistic curve that can be used as a selectivity function, or maturity curve, of wherever a logistic is required. This version uses the logistic function 1/(1+exp(-log(19.0)*(lens-inL50)/(inL95-inL50))), which explicitly defines the SM50 and uses SM95 as the second parameter.

Usage

logist(inL50, delta, depend, knifeedge = 0)

Arguments

inL50	is the length at 50 percent selection/maturity/whatever
delta	is the difference in selection/maturity/whatever between inL50 and inL95
depend	a vector of lengths/ages for which the logistic value will be calculated.
knifeedge	defaults to 0. If knifeedge is set to a particular length or age then the logistic value <= the value of knifeedge is set to zero, which is essentially knife-edge. Allows for knife-edge selectivity

Value

A vector of length(depend) containing the predicted logistic values

Examples

## Not run: 
in50 <- 100.0
deltaS <- 8.0
lens <- seq(2,210,2)
select <- logist(inL50=in50,delta=deltaS,depend=lens)
selectk <- logist(in50,deltaS,lens,knifeedge=105)
round(cbind(lens[35:70],select[35:70],selectk[35:70]),5)

## End(Not run) 

haddonm/datalowSA documentation built on Nov. 5, 2023, 6:40 p.m.