I am a new user of R. I am attempting to use R to explore a set of equations specifying the dynamics of a three trophic level food chain. I have put together this code for the function that is to be evaluted by LSODA. My equations Rprime, Cprime, and Pprime are meant to describe the actual equation of the derivative. When I run LSODA, I do not get the output that these equations should be giving. Can someone tell me if I have set this function up correctly to use with LSODA when the user is specifying the equation of the derivative or offer some advice for using LSODA in R? An example of how to code for user specified differential equations would be great.
function(times,y,p)
{
Rprime <- (R*(1-R))-((xc*yc*C*R)/(R+R0))-((w*xp*ypr*P*R)/(R02+((1-w)*C)+(w*R)))
Cprime <- (-1*(xc*C)*(1-(yc*R)/(R+R0)))-(((1-w)*xp*ypc*P*C)/((w*R)+((1-w)*C)+C0))
Pprime <- (-1*P)-(((1-w)*xp*ypc*C*P)/((w*R)+((1-w)*C)+C0))+((w*xp*ypr*P*R)/((w*R)+((1-w)*C)+R02))
list(c(Rprime, Cprime, Pprime))
}
The above is the function yprime which the documentation for the odesolve says that I may specify.
Thanks for any help that anyone can provide.
Ivan Kautter
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