There was a spurious tilde in the code coming
from my digital signature -- oops. ignore the
tilde in the function:
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])
stephen sefick wrote:
error in isoda(y = 1, times = seq(0, 1, by = 0.02), func = e1B, parms
= c(b = 0.9)) :
Model function must return a list
this is the error message I get when I try and paste in the code.
Stephen Sefick
On Mon, Aug 11, 2008 at 1:36 PM, Ben Bolker <[EMAIL PROTECTED]> wrote:
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 <[EMAIL PROTECTED]> 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])
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