[R-sig-dyn-mod] DDEs in simecol?

[Thomas Petzoldt]

Hello James,

yes this is possible if you specify a user-defined solver function. This 
is easy, because for class odeModel, simecol is just an object oriented 
wrapper for package deSolve, that does the real work.

If you use simecol or plain deSolve has its pros and cons and is a 
matter of taste. deSolve alone is a little bit easier, but simecol can 
help to make to applications more structured, e.g. in case of model 
comparisons.

Thomas


### Simple DDE, adapted version of ?dede
### example from package deSolve

library(simecol)

model <- new("odeModel",
   main = function(t, y, parms) {
     with(as.list(parms), {
       if (t < tau)
         ytau <- 1
       else
         ytau <- lagvalue(t - tau)

       dy <- k * ytau
       list(c(dy), ytau=ytau)
     })
   },
   init = c(y=1),
   times = seq(0, 30, 0.1),
   parms = c(tau = 1, k = -1),
   solver = function(init, times, func, parms) {
     dede(init, times, func, parms)
   }
)

model <- sim(model)

plot(model, main = c("dy/dt = -y(t-1)", "ytau"))