[R] Differential Equations there use in R (population modeling)
Ben Bolker
bolker at ufl.edu
Mon Aug 11 19:36:21 CEST 2008
BEGIN PGP SIGNED MESSAGE
Hash: SHA1
stephen sefick wrote:
 population# = (initialvalue @ t)  (death rate) + (fecundtity per
individual) dt
 to be able to vary the values of the inputs death rate and fecundity
 with time using initial value @ t from the previous time step to
 evaluate the function at the present time step.

 On Mon, Aug 11, 2008 at 9:43 AM, Ben Bolker <bolker at ufl.edu> wrote:
> stephen sefick <ssefick <at> gmail.com> writes:
>
>> e1 < function(x,b,t){
>> d<(x)*(b^t)
>> plot(d)
>> }
>>
>> e1(2, 2,seq(from=0, to=6, by=1))
>>
>> Is there a way to do this with a change in time. I would like to use
>> differential equations.
> I'm not sure what you mean by "do this with a change in time",
> but in general for ODEs you should check out lsoda in the odesolve
package.
> You can also look at the ecology/environment task view.
>
> Ben Bolker
>
~ Something like:
library(odesolve)
## in general x, b are state and parameter VECTORS
e1B < function(t,x,b) {
~ list(x*b^t,NULL)
}
L1 = lsoda(y=1,times=seq(0,1,by=0.02),func=e1B,parms=c(b=0.9))
plot(L1[,1],L1[,2])
BEGIN PGP SIGNATURE
Version: GnuPG v1.4.6 (GNU/Linux)
Comment: Using GnuPG with Mozilla  http://enigmail.mozdev.org
iD8DBQFIoHiVc5UpGjwzenMRAs+DAJ9kekwPnnlVE8mAMa61OmCkl0E2fACgiCy3
L/oQ3zIonFXAcGmvugXjTdE=
=GQFi
END PGP SIGNATURE
More information about the Rhelp
mailing list