You did not provide the data or a way of generating it. I would guess that Excel finds the same solution (the same residual sum-of squares) as nls but that it uses a weak convergence criterion and/or does not give you information regarding why it terminates.
Regarding the step size: you can set the minimum step size factor via the minFactor argument of control. qx.suav <- function(id,A,B,C,D,E,F,G,H,K) (A^((id+B)^C)+(D*exp(-E*(log(id)-log(F))^2))+(G*H^id)/(1+(K*G*H^id))) ## make noisy data from model id <- 1:1000 tx.br <- qx.suav(id,A=0.0006347,B=0.0453814,C=0.1353538,D=0.1353538, E=0.0002127,F=38.5448420,G=0.0000115,H=1.1109286, K=0.382070638) set.seed(1) tx.br <- tx.br + rnorm(length(tx.br),0,.0001) HP <- nls(tx.br~qx.suav(id,A,B,C,D,E,F,G,H,K), data=data.frame(id=id,tx.br=tx.br), trace=TRUE,nls.control(maxiter=5000,warnOnly=TRUE), algorithm='port', start=list(A=0.0006347,B=0.0453814,C=0.1353538,D=0.1353538, E=0.0002127,F=38.5448420,G=0.0000115,H=1.1109286, K=0.382070638), lower=list(A=0,B=0,C=0,D=0,E=0,F=0,G=0,H=0,K=0)) matplot(cbind(fitted(HP), tx.br),type="l") On Thu, 10 Dec 2009, AneSR wrote: > > I have a non-linear regression with 8 parameters to solve .... however it > does not converge ... easily solves the excel ... including the initial > estimates used in the R were found in the excel ... Another question is how > to establish the increments of R by the parameters in the search .. > > > qx.suav<-function(id,A,B,C,D,E,F,G,H,K){(A^((id+B)^C)+(D*exp(-E*(log(id)-log(F))^2))+(G*H^id)/(1+(K*G*H^id)))} > HP<-nls(tx.br~qx.suav(id,A,B,C,D,E,F,G,H,K),data=data.frame(id=id,tx.br=tx.br), > trace=TRUE,nls.control(maxiter=5000),algorithm='port',start=list(A=0.0006347,B=0.0453814,C=0.1353538,D=0.1353538,E=0.0002127,F=38.5448420,G=0.0000115,H=1.1109286,K=0.382070638),lower=list(A=0,B=0,C=0,D=0,E=0,F=0,G=0,H=0,K=0)) > summary(HP) > > How to solve this problem in R? > > Ane > -- > View this message in context: > http://n4.nabble.com/non-linear-regression-tp959977p959977.html > Sent from the R help mailing list archive at Nabble.com. > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. > ______________________________________________ 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.