similar to: PKPD modelling in R

Hello! I would like to know if R can solve Differential Equations... I don't think so because, in my point, I see R like a Statistical System, not a Math System. Am I wrong? Thank you very much. M??rcio de Medeiros Ribeiro Graduando em Ci??ncia da Computa????o Departamento de Tecnologia da Informa????o - TCI Universidade Federal de Alagoas - UFAL Macei?? - Alagoas - Brasil Projeto CoCADa

Dear Colleagues, Our group is also working on implementing the use of R for pharmacokinetic compartmental analysis. Perhaps I have missed something, but > fit <- nls(noisy ~ lsoda(xstart, time, one.compartment.model, c(K1=0.5, k2=0.5)), + data=C1.lsoda, + start=list(K1=0.3, k2=0.7), + trace=T + ) Error in eval(as.name(varName), data) : Object

Hello R Developers, This is my first foray into using c-code with R, so please forgive my foolishness. I had a look at the archives and did not find anything on this, so hopefully I am not doubling up. I have tried to use R cmd to create an object file from the odesolve dynload example. I am using windows and have just installed rtools, and have the latest version of stable R (2..7.2). This is

Hello List, Can you recommend me if odeSolve can handle stiff delay differential equations with discontinuities? Or any other package? Best, -m

Dear list - Does anyone have any ideas / comments about why I am receiving the following warning when I run lsoda: 1: lsoda-- at t (=r1), too much accuracy requested in: lsoda(start, times, model, parms) 2: for precision of machine.. see tolsf (=r2) in: lsoda(start, times, model, parms) I have tried changing both rtol and atol but without success. I saw the thread in the

Hello, I want to know if there are some functions or packages to solve differential and integral equation using R. Thanks. Shao chunxuan. [[alternative HTML version deleted]]

I am trying to use nlmeODE. But I don't know what is ObsEq. How you can get it from your ODEs system? Could someone help me out? Best, Ron

Dear list, I have a degradation model: dX/dt = * I(X2)*( k1*X(t) )/( X(t)+k2 ) where X(t) is concentration at time t, and k1 and k2 are parameters that I want to estimate. I(X) is a known inhibitor function. My questions is whether this is implemented or easily computed in any R package. I have searched the archives but without luck. Any help or comments on this would be appreciated, Klaus

Dear All,   Currently I am running the following code:   library(stats4) library(odesolve) library(rgenoud) Input<-data.frame(SUB=c(1),time=c(0.5,3,10,15),lev=c(2.05,12.08,9.02,8)) XD<-500 IT<-3 diffeqfun<-function(time, y, parms) {   if(time<=IT)      dCpdt <- (XD/IT)/parms["Vol"] -

Hello list I have a theoretical differential equation model (two coupled differential equations) describing the acidification of dairy cultures in milk: dX/dt = f(H, param)*X dH/dt = g(param)*dX/dt pH = -log10(H) I also have actual data of the same. I would like to estimate the parameters of the theoretical model from real data, but don't know how to go about it in R (I'm fairly new

Hi all, I try to assess the parameters (K1,K2) of a model that describes the adsorption of a molecule onto on adsorbent. equation: dq/dt = K1*C*(qm-q)-K2*q I know the value of 'qm' and I experimentally measure the variables 'q', 'C', and the time 't'. t C q 1 0 144.05047 0.0000000 2 565 99.71492 0.1105625 3 988 74.99426

A couple of minor points about the odesolve package (which I am otherwise enjoying very much): 1. "scalar" is misspelled as "scaler" in the definitions of the rtol and atol parameters 2. it is possible to crash R by doing something dumb, e.g failing to read the documentation carefully enough and (a) returning only a vector of derivatives and not a list of (derivatives,

All- I am interested in estimating a parameter that is the starting value for an ODE model. That is, in the typical combined fitting procedure using nls and lsoda (alternatively rk4), I first defined the ODE model: minmod <- function(t, y, parms) { G <- y[1] X <- y[2] with(as.list(parms),{ I_t <- approx(time, I.input, t)$y dG <- -1*(p1 + X)*G +p1*G_b dX <-

Hi, I just installed the odesolve package and ran the check command on it. It failed trying to execute library(gnlm). Sure enough, there is no gnlm library on my system and I could not find it on the CRAN archive either. Am I missing anything obvious or is gnlm some private library that somehow found its way into the example section of odesolve? Thanks in advance, Andy

Dear All, I like to simulate a physiologically based pharmacokinetics model using R but am having a problem with the daspk routine. The same problem has been implemented in Berkeley madonna and Winbugs so that I know that it is working. However, with daspk it is not, and the numbers are everywhere! Please see the following and let me know if I am missing something... Thanks a lot in advance,

Hi everybody I'm new in the forum and i need some help well i just started to used ubuntu 9.04 and wine 1.x in order to run win only-supported programs, but when i try to run a game call Mu Magdalena (Per?) it show me the follow message: nelson at yaltasoplin-desktop:~$ wine C:\\Archivos\ de\ programa\\Mu\ Magdalena\\Main fixme:reg:GetNativeSystemInfo (0x846cd9c) using GetSystemInfo()

I have a package that solves systems of ordinary differential equations coded as an R function (odesolve, on CRAN). The function is passed to R code, and c and Fortran code called by it uses lang4() and eval() to evaluate the R function inside a compiled c function to use in a compiled ODE solver. This works quite well, but can be slow. I'd like to be able to supply the name of a compiled

I'm trying to use odesolve for integrating various series of coupled 1st order differential equations (derived from a system of enzymatic catalysis and copied below, apologies for the excessively long set of parameters). The thing that confuses me is that, whilst I can run the function rk4: out <- rk4(y=y,times=times,func=func, parms=parms) and the results look not unreasonable:

Dear All A new non-linear mixed-effects modelling package for R called nlmeODE is now available at www.cran.r-project.org and http://nlmeODE.sourceforge.net. It combines Pinheiro and Bates' NLME library in R with an ordinary differential equations (ODE) solver thereby enabling the use of differential equations in population PK/PD modelling. It includes several PK examples such as one- and

Dear R-helpers, I have some problem with a model I am trying to run with nlmeODE. I have a covariate that I want to include in the model and I can't find in the documentation how to include it in the model so that it can calculate it. >formula(trial) PME ~ time | Ident abcnoniso <- list(DiffEq=list( debdt = ~ -ksol*pH*eb , desdt = ~