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 drug administration. That is to say, not only 100 at t=0 but also at t=20,40,... I can't find a solution to do so. I tried adding "100" to the first differential equation at the times of interest but it doesn't work. Do you have any idea? Thank you F.G.
Differential equations
3 messages · Fanny Gallais, Peter Dalgaard, Thomas Petzoldt
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 Feb 2017, at 11:10 , Fanny Gallais <gallais.fanny at gmail.com> wrote:
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 drug administration. That is to say, not only 100 at t=0 but also at t=20,40,... I can't find a solution to do so. I tried adding "100" to the first differential equation at the times of interest but it doesn't work. Do you have any idea? Thank you F.G. [[alternative HTML version deleted]]
______________________________________________ R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Office: A 4.23 Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com
17 days later
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.
http://desolve.r-forge.r-project.org/user2014/tutorial.pdf
Thomas Petzoldt
See also:
http://desolve.r-forge.r-project.org
https://stat.ethz.ch/mailman/listinfo/r-sig-dynamic-models
Am 08.02.2017 um 16:19 schrieb peter dalgaard:
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 Feb 2017, at 11:10 , Fanny Gallais <gallais.fanny at gmail.com> wrote:
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 drug administration. That is to say, not only 100 at t=0 but also at t=20,40,... I can't find a solution to do so. I tried adding "100" to the first differential equation at the times of interest but it doesn't work. Do you have any idea? Thank you F.G. [[alternative HTML version deleted]]
______________________________________________ R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.