thanks
On Mon, Aug 11, 2008 at 2:18 PM, Ben Bolker <[EMAIL PROTECTED]> wrote:
>
> 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])
>>
>>
>>>
>
>
--
Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals.
-K. Mullis
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