search for: nlin

I am running a 3-parameter nonlinear fit using the default Gauss-Newton method of nls. initialValues.L = list(b=4,d=0.04,t=180); fit.nls.L = nls( myModel.nlm , fData.L, start = initialValues.L, control = nls.control(warnOnly = TRUE), trace=T ); summary.nls.L = summary(fit.nls.L); I run the same analysis in SAS proc NLIN. pro...

Dear Sir, I am working with one example in R donlp2. How I can get the Hessian matrix from the output. p = c(10,10) par.l = c(-100,-100) par.u = c(100,100) nlin.l = nlin.u = 2 fn = function(x) { x[1]^2+x[2]^2 } dfn = function(x){ c(2*x[1], 2*x[2]) } attr(fn, "gr") = dfn nlcon = function(x){ x[1]*x[2] } dnlcon = function(x){ c(x[2], x[1]) } attr(nlcon, "gr") = dnlcon donlp2.control = function(hessian = TRUE) ret = donlp2(p, fn, p...

Hello R folks, I'm hoping the answer to the question in the subject line. I have in the past used SAS PROC NLIN and PROC NLP to carry out nonlinear optimizations. I'm wondering if there is analogous ways for doing this using R. If so, could someone please point me to some literature that would help me examine this further? Thanks very much. [[alternative HTML version deleted]]

...ion when asking for access. JN > Date: Tue, 16 Feb 2010 11:09:35 -0500 > From: "Powers, Randall - BLS" <Powers.Randall at bls.gov> > To: <r-help at r-project.org> > Subject: [R] Does the R "statistical language includes > modules/packages to carry out nonlinear optimization similar to the > SAS NLIN and NLP procedures? > Message-ID: > <C3C1925D945BF844911C8EEA752666AE20A788E5 at psbexmb2.psb.bls.gov> > Content-Type: text/plain > > Hello R folks, > > I'm hoping the answer to the question in the subject line. > &...

...n some restrictions on the input. I would like to know if there is a way to impose some restrictions on 'intermediate variables' of the function. An example.. fx = function (x) { s <- 0 for (i in 1:3) { s <- x[i]^3 + s } s } optim(rep(4,3), method="L-BFGS-B", lower=rep(-10,nlin), upper=rep(10,nlin)) It would return '-10' for all variables. I want, however, a solution satisfying mean(x)>7. Please, don't analyse this specific example, but the logic of satisfying a criterium for the mean of the input (with thousands of variables). My real problem involves pri...

---- Original message ---- >Date: Thu, 14 Jul 2005 19:50:41 +0200 >From: Uwe Ligges <ligges at statistik.uni-dortmund.de> >Subject: Re: [R] East Asian language >To: Nan Lin <nlin at math.wustl.edu> >Cc: r-help at stat.math.ethz.ch > >Nan Lin wrote: > >> Dear all, >> >> I just installed R 2.1.1. The installation program automatically recognized >> my Windows XP was using Chinese language, so now my R console displays >> everyth...

Do I have the right impression that it's currently not possible to produce confidence intervals for the nls predictions using R? I had a course were we used SAS PROC nlin and there you could get intervals for the parameters and the prediction but I do not have access to SAS. Would it be difficult to implement, I tried to dig into the help pages of nls, vcov and nlsModel but I could not really make sense out of this? ---------------------------------------------...

...el with unknown joint points in nls and perhaps eventually in nlme. I can fit this model in sas (see below, joint points to be estimated are a41 and a41), but am unsure how to specify this in the nlm function. I would really appreciate any suggestions or example code. Thanks a lot. -andy proc nlin data=Stems.Trees; params b41=-3 b42=1.5 b43=-1.5 b44=50 a41=0.75 a42=0.1; term1 = (b41*(x - 1) + b42*(x**2 -1)); if (a41 - x) >= 0 then term2 = (b43*(a41 - x)**2); else term2 = 0; if (a42 - x) >=0 then term3 = (b44*(a42 - x)**2); else term3 = 0; model y = term1+term2+term3...

Hi all, I'm trying to fit a nonlinear (logistic-like) regression, and I'd like to get some recommendations for which package to use. The expression I want to fit is something like: y ~ A * exp(X * Beta1) / (1 + exp(-(x + X * Beta2 - xmid)/scal)) Basically, it's a logistic function, but I want to be able to modify the satu...

Dear all I''m not sure is this question has much sense, but I''m working with nonlinear models using the nlme library (gnls fit for different groups) and I''m wondering if I can get the values of R-squared for each fit. I''ll appreciate any comment. Thanks in advance C. Mora

Hi, Dear R community, These is a paper of "Wheat Grain Yield Response to N Application Evaluated through Canopy Reflectance". This paper of "Materials and Methods" said "A single regression equation relating A and B was derived for each location using PROC NLIN (SAS Inst. 1990). Slopes and intercepts for the independent regressions were compared with an *approximate F-test* (Mead et al. 1993) to determine if a single relationship could be used across environments." I can not understand the "approximate F-test", and I donot know how to use...

Among others, datam contains the columns: logconc, tm, dose, subj, bilirubin. None of these are factor variables. The following compartment models work (the first still has not converged after 100 interations): res1 <- nlme(logconc~p2+p3+log(dose/(exp(p1)-exp(p2))* (exp(-exp(p2)*tm)-exp(-exp(p1)*tm))),start=list(fixed=c(5,-2,-0.1)), fixed=list(p1+p2+p3~1),control=list(maxIter=100),

Hello! Disapointed about SPSS I have to choose another statistic program. And altough I sympathise with the idea of a non-commercial software-project like R and I like the spirit of the R community (and of course I am not keen on paying 150$ to SAS for a one-year students license), I will probably buy SAS, because people I will work with use SAS and I want a close cooperation with them. Besides I