ID1 ID2 t V(t) 1 1 0 6.053078443 2 1 0.3403 5.56937391 3 1 0.4181 5.45484486 4 1 0.4986 5.193124598 5 1 0.7451 4.31386722 6 1 1.0069 3.645422269 7 1 1.5535 3.587710965 8 1 1.8049 3.740362689 9 1 2.4979 3.699837726 10 1 6.4903 2.908485019 11 1 13.5049 1.888179494 12 1 27.5049 1.176091259 13 1 41.5049 1.176091259
The model (1) V(t)=V0[1-epi+ epi*exp(-c(t-t0))] (2) V(t)=V0{A*exp[-lambda1(t-t0)]+(1-A)*exp[-lambda2(t-t0)]} in formula (2) lambda1=0.5*{(c+delta)+[(c-delta)^2+4*(1-epi)*c*delta]^0.5} lambda2=0.5*{(c+delta)-[(c-delta)^2+4*(1-epi)*c*delta]^0.5} A=(epi*c-lambda2)/(lambda1-lambda2) The regression rule : for formula (1):(t<=2,that is) first 8 rows are used for non-linear regression epi,c,t0,V0 parameters are obtained for formula (2):all 13 rows of results are used for non-linear regression lambda1,lambda2,A (with these parameters, delta can be calculated from them) Thanks for help Ster Lesser -- View this message in context: http://r.789695.n4.nabble.com/nls-problem-with-R-tp3494454p3497825.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.