Hi,
yes, the suggestion of Peter Dalgaard is correct, and it can also be
done using the "event" mechanism of deSolve, see:
library("deSolve")
?events
... or the slides from our talk given at useR-2011
http://desolve.r-forge.r-project.org/slides/petz_soet2011.pdf
... or the tutorial from L.A
It's been a while, but I think I have gotten through this sort of situation by
splitting the integration into intervals, i.e., you run from t=0 to t=20 witn
initial condition c(100,0), yielding a value c(y1,y2), then you run from 20 to
40 with initial condition c(y1+100, y2), etc.
-pd
On 08 Fe
Hi,
I'm working on a system of 2 differential equations. My initial condition
(t=0) is c(100,0) and i'm using lsoda function (from package deSolve) to
solve it.
My system reprensents the evoution of drug concentration in two
compartments throug time. Problem is I would like to model a repeated dru
Hi,
stephen sefick wrote:
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 am trying to model
a population with an initial value, fecundity per time st
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.
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(
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:
> -BEGIN PGP SIGNE
-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
| eval
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, Be
stephen sefick 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 chan
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 am trying to model
a population with an initial value, fecundity per time step, and a
death rate. The ab
I just got 37 hits from RSiteSearch('differential equation',
'fun') including odesolv{fda}, rk4{deSolve}, rk4{odesolve}, in addition
to lsoda{odesolve} and the Rsundials package.
hope this helps.
Spencer Graves
Michael Lawrence wrote:
On Tue, Jun 17, 2008 at 6:25 PM, David Ar
On Tue, Jun 17, 2008 at 6:25 PM, David Arnold <[EMAIL PROTECTED]>
wrote:
> All,
>
> I've found odesolve and lsoda.
>
> Any other packages for differential equations?
>
There's Rsundials, which gives you an algebraic ode solver.
>
> Any good tutorials on using R and solving differential and part
hi , David.
I think odesolve is what you need , do you ever try it ?
Solving differential equations is not a strong function of R, that
means,
maybe you should try to write your own procedure using your own
numerical
method for your own specific equation .
regards.
On 2008-6-18, at 上午9:25,
All,
I've found odesolve and lsoda.
Any other packages for differential equations?
Any good tutorials on using R and solving differential and partial
differential equations?
D.
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