Dear Berend and Thomas, thank you for suggesting the lsei function. I found that the tlsce {BCE} function also works very well:
library("BCE") tlsce(A=bmat,B=target) The limSolve package has an 'xsample' function for generating uncertainty values via Monte-Carlo simulation, however it only works when specifying the standard deviation on the target data (B). In my situation I have standard deviations for the source areas (A) only. Therefore I need to generate the uncertainty values manually. I've created a matrix of 1000 randonly distributed numbers for each of the source area (A) properties: TSCa<-matrix(rnorm(1000, mean=0.03, sd=0.005),ncol=1) TSMg<-matrix(rnorm(1000, mean=0.0073, sd=0.002),ncol=1) CBCa<-matrix(rnorm(1000, mean=0.6, sd=0.1),ncol=1) CBMg<-matrix(rnorm(1000, mean=0.0102, sd=0.005),ncol=1) RCa<-matrix(rnorm(1000, mean=0.2, sd=0.05),ncol=1) RMg<-matrix(rnorm(1000, mean=0.0141, sd=0.005),ncol=1) DCa<-matrix(rnorm(1000, mean=0.35, sd=0.1),ncol=1) DMg<-matrix(rnorm(1000, mean=0.012, sd=0.004),ncol=1) DistAll<-cbind(TSCa,TSMg,CBCa,CBMg,RCa,RMg,DCa,DMg) colnames(DistAll)<-c("TopSoilCa","TopSoilMg","ChannelBankCa","ChannelBankMg","RoadCa","RoadMg","DrainCa","DrainMg") I now want to run the lsei model again: lsei(A=bmat,B=target,E=matrix(rep(1,4),ncol=4),F=1,G=matrix(rep(1,4),ncol=4),H=0, fulloutput=TRUE)) but with A=bmat replaced by the appropriate random values in DistAll. I assume I could then use the function "replicate" to then run the model 1000 times to generate uncertainty values, e.g. replicate(n=1000,lsei(A=bmat,B=target,E=matrix(rep(1,4),ncol=4),F=1,G=matrix(rep(1,4),ncol=4),H=0, fulloutput=TRUE)) Would anyone be able to help me write a function to replace bmat with new values from DistAll each time the lsei model is run? Many thanks in advance Richard -- View this message in context: http://r.789695.n4.nabble.com/Optimization-in-R-similar-to-MS-Excel-Solver-tp4646759p4647524.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list 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.