srfunctions: SR funcitons

In eeholmes/DM: Dynamic Model

Description

Takes the S, LOG flow, LOG marine survival covariates and p parameters and returns the recruits based on the specified SR function: ricker(), bevertonHolt(), hockeyStick(). Note that it assumes that the log of the covariates are input. All covariates appear in the form exp(p*cov). p[1]=log a; p[2]=log b. The other p are the covariate coefficients.

Usage

ricker(S, covariates, p)

bevertonHolt(S, covariates, p)

hockeyStick(S, covariates, p)

Arguments

S	spawner count
covariates	A list with the covariates. The ms covariate is normally the first and the flow covariate is the second. Though order does not matter as the p's are matched based on order the covariate appears in the list.
p	the SR function a, b, and the coefficients for each covariate in the covariate list. All covariates appear in the form exp(exp(p)*cov). p[1]=a; p[2]=b. The other p match the covariates.

Value

recruits (scalar)

recruits from ricker: S*exp(p[1])*exp(-S/exp(p[2]))*exp(p[4]*flow)*exp(p[3]*marineInd)

recruits from beverton Holt: S/(S*exp(-p[2])+exp(-p[1]))*exp(p[4]*flow)*exp(p[3]*marineInd)

recruits from hockey stick: ifelse(exp(p[1])*S<exp(p[2]),exp(p[1])*S,exp(p[2]))*exp(p[4]*flow)*exp(p[3]*marineInd)

eeholmes/DM documentation built on May 26, 2019, 3:36 p.m.