expon.model.functions: Functions to define exponential models for simulation

Description Usage Arguments Details Value Note Author(s) References See Also Examples

Description

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

Usage

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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

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.

Value

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

Note

Model functions are employed mainly to define the ODE to be simulated by sim.comp, sim.mruns, sim.rnum, sim, simd and other simulation functions.

Nominal parameter values are defined in input files. Variation of param values are defined in lists.

Input files are in 'datafiles.zip' in directory 'datafiles' and organized by chapters of Acevedo (2012). Input files are required to run the examples below.

Author(s)

Miguel F. Acevedo Acevedo@unt.edu

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

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## Not run: 
# 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)

## End(Not run)

seem documentation built on April 14, 2017, 9:12 p.m.