SEIRS epidemic model

Simulation of an epidemic by classical deterministic models: SI, SIS, SIR, SIRS, SEIR, SEIRS

The contribution contains the class epidemic by which one can simulate the evaluation of an epidemic by several classical deterministic epidemic models without vital dynamics:
SI -- Susceptible->Infective
SIS -- Susceptible->Infective->Susceptible
SIR -- Susceptible->Infective-Removed
SIRS -- Susceptible->Infective->Removed->Susceptible
SEIR -- Susceptible->Exposed->Infective->Removed
SEIRS -- Susceptible->Exposed->Infective->Removed->Susceptible

Usage
obj = epidemic(model, varargin)
model -- {'SI,'SIS','SIR','SIRS', SEIR','SEIRS'}
'beta',beta -- contact frequency (>0) - for all models
'gamma',gamma -- removal frequency (>0) - for all models except SI
'sigma',sigma -- incubation frequency (>0) - for SEIR and SEIRS models
'xi', xi -- returning frequency (>0) - for SIS, SIRS and SEIRS models
'tend',tend -- end time (>0, defTime)
'dt',dt -- integration step (>0, def 0.1)
'N',N -- population size (>0, def 1000)
'I0',I0 -- initial number of infectious (>=0, def 1)
'E0',E0 -- initial number of exposed (>=0, def 0)

Methods
run(obj,varargin) -- run simulation
'tend',tend -- end time (>0, def ...)
'dt',dt -- integration step (>0, def 0.1)
'N',N -- population size (>0, def 1000)
'I0',I0 -- initial number of infectious (>=0, def 1)
'E0',E0 -- initial number of exposed (>=0, def 0)
plot(obj,varargin) -- plot result of simulation
'all',{'on','off'} -- plot all populations or just total cases (def 'on')
'new',{'on','off'} -- new plot (def 'on')
'total' ,{'on','off'} -- plot also total cases if 'all','on'

Example:
aa=epidemic('SEIR','N',200,'beta',1.9,'gamma',1/5,'sigma',1/7,'tend',60);
run(aa)
plot(aa)

No parameterization function is provided for actual data.

DISCLAIMER: Software is for education and not for medical or commercial use. Use it at your own discretion.