get_diff: Calculate the derivative of C in getMNPL()

In mcsiple/mmrefpoints: Project Marine Mammal Populations and Calculate Reference Points

Calculate the derivative of C in getMNPL()

Description

this is the function to minimize, but needs to be restricted to that yield > 0 All life history params are as above

Usage

get_diff(
  logit.E,
  S0 = S0.w,
  S1plus = S1plus.w,
  AgeMat = AgeMat.w,
  nages = nages.w,
  A = A.w,
  z = z.w
)

Arguments

logit.E	logit transform of bycatch mortality
S0	Calf/pup survival, a numeric value between 0 and 1
S1plus	adult survival, a numeric value between 0 and 1
AgeMat	Age at maturity (= age at first parturition - 1)
nages	"maximum" age, treated as the plus group age. The plus group age can be set equal to the age at maturity +2 years without losing accuracy.
A	the Pella-Tomlinson resilience parameter ((fmax - f0)/f0)
z	Degree of compensation (also known as the Pella-Tomlinson parameter)

Examples

S0.w = 0.5; S1plus.w = 0.944; nages.w = 25; AgeMat.w = 18 
InitDepl.w = 0.9; z.w = 2.39; lambdaMax.w = 1.04
# Get A parameter
NPROut <- npr(S0 = S0.w, S1plus = S1plus.w, nages = nages.w, AgeMat = AgeMat.w, E = 0)
N0 <- NPROut$npr # mature numbers per recruit
Fec0 <- 1.0 / N0
fmax <- getfecmax(lambdaMax = lambdaMax.w, S0 = S0.w, S1plus = S1plus.w, AgeMat = AgeMat.w)
A.w <- (fmax - Fec0) / Fec0
# Get number of individuals per recruit in terms of mature individuals (\eqn{N0.w})
get_diff(
 logit.E = logit(0.01), S0 = S0.w, S1plus = S1plus.w, nages = nages.w, A = A.w, AgeMat = AgeMat.w, 
  z = 2.39
)

mcsiple/mmrefpoints documentation built on June 17, 2022, 8:41 p.m.