On Feb 10, 2013, at 3:35 PM, Jannetta Steyn wrote:
I managed to get it to work (I think). Code below:
The output certainly looks more sensible. You commented out the if-
reset strategy and are using events. Can you explain how the event
code is triggered? I no longer see a definition of a v>=30 trigger.
The vignette says "Events occur when the values of state variables are
instantaneously changed. They can be specified as a data.frame, or in
a function. Events can also be triggered by a root function." Is the
code detecting the sudden rise to infinite values and using that as
the trigger for a reset?
--
David.
library(deSolve);
Izhikevich <- function(time, init, parms) {
with(as.list(c(init, parms)),{
dv <- (0.04*v^2)+(5*v)+140-u+I;
du <- a*(b*v-u);
#if (v>=30) v<-c else v<-u+d;
list( c(dv, du))
})}
parms=c( a=0.02, b=0.2, c=-65, d=2, I=4);
times=seq(from=1, to=500, by=0.1);
init=c(v=-65, u=0.2);
root <- function(time, init, parms) init[1]
event <- function(time, init, parms) {
with(as.list(c(init, parms)), {
init[2] <- init[1] + d
init[1] <- c
return(init)
})
}
out<-ode(y=init, times=times, func=Izhikevich, parms=parms,
events=list(func=event, root=TRUE), rootfun=root)
plot(out)
Thanks everybody for their help.
Jannetta
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David Winsemius, MD
Alameda, CA, USA
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