seem (version 1.0)

Exponential Model Functions: Functions to define exponential models for simulation

Description

Functions used as part of argument model to call simulation functions.

Usage

expon(t,p,x)
expon.rand(t,p,x)
expon.forced(t,p,x)
expon.var(t,p,x)
expon.z(t,p,x)
expon.g(t,p,x,tz)

Arguments

t

time

p

parameters, an array

x

state variable

tz

times of sudden disturbance

Value

• Rate of change or derivative of model. Except expon.z and expon.g that return disturbance regime.

Details

State variable can be population density, or chemical concentration. For expon, p is dim 1: the rate coeff. For expon.rand, p is dim 2: mean and sdev of rate coeff. For expon.forced, p is dim 3: rate coeff and disturbance parameters. For expon.var, p is dim 4: mean, drift coeff, amplitude, and period of sinusoidal variation.

Functions expon.z and expon.g define discontinuous disturbance regime. Function expon.z defines times of discontinuities, and expon.g applies a linear disturbance at tz times defined by expon.z.

References

Acevedo M.F. 2012. Simulation of Ecological and Environmental Models. CRC Press.

See Also

Simulation functions sim.comp, sim.rnum, sim.mruns, sim, simd Methods euler, RK4

Examples

# exponential
model <- list(f=expon)
# single run
file<-"chp4/exp-pop-inp.csv"
out <- sim.comp(model,file)
# multiple runs
param <- list(plab="r", pval = seq(-0.02,0.02,0.01))
out.r <- sim.mruns(model, file, param)
# Monte Carlo run
model <- list(f=expon.rand)
file<-"chp4/exp-rnum-inp.csv"
out.rk <- sim.rnum(model,file)
# Harvest, multiple runs 
exp.f <- list(f=expon.forced)
param <- list(plab="Ha",pval=c(0,-0.1,-0.2))
t.X <- sim(exp.f,"chp7/exp-harvest-inp.csv",param)
# Seasonality 
exp.v <- list(f=expon.var)
param <- list(plab="rd",pval=c(0,-0.005,-0.01))
t.X <- sim(exp.v,"chp7/exp-var-inp.csv",param)
# sudden disturbance
exp.sud <- list(f=expon,z=expon.z,g=expon.g)
param <- list(plab="Ha",pval=c(-10,-20,-30))
t.X <- simd(exp.sud,file="chp7/exp-sud-inp.csv",param)