search for: nonlinear

Displaying 20 results from an estimated 1099 matches for "nonlinear".

2004 Feb 24
5
Nonlinear Optimization
Hi, I have been brought back to the "R-Side" from MatLab. I have used R in graduate econometrics but only for statistics and regression (linear and nonlinear). But now I need to run general nonlinear optimization. I know about the add-in quadprog but my problem is not QP. My problem is a general nonlinear (obj funct) with linear constraints.I know about the "ms" and "nls" functions, but these seem only for nonlinear regression, not...
2009 Feb 17
1
Processing a list of fit objects
Hi, I have a list of fit objects (fit objects from HMISC functions) I create elements in the list in this way lrm.sumtot <- lrm( ae7bepn ~ trarm + sumtot , data=sd.fix) lrm.list[['lrm.sumtot']] <- lrm.sumtot And I can run (anova(lrm.sumtot)) The following also gives the anova I'd expect zz <- lrm.list[['lrm.sumtot']];anova(zz) And similarly for the summary
2008 Dec 24
3
statistical significance, nonlinear regression
I am using nonlinear regression to fit a couple of variables to a set of measurements. I would like to do some significance tests for the estimated parameters. I am able to check the confidence intervals using the Jacobian coming out of nonlinear regression. I do see in a paper which shows t-value (it says estimated...
2003 Apr 21
4
nonlinear equation solver?
Dear R-Help, I am trying to use R to solve a nonlinear equation many times for different values. I am looking for a mathematical nonlinear equation solution which may not have a closed solution form. For example, I have equation: 2 = (t^2)/log(t) What is t? I am wondering how to solve it in R. Many thanks, Zhu Wang Statistical Science Department...
2005 May 27
1
Testing Nonlinear Restrictions
Dear all, I'm interested in testing 2 nonlinear restrictions on coefficients of a nls object. Is there a package for doing this? Something in the lines of `test(nls object, res=c("res 1","res 2"),...)' I only found the function delta.method in the alr3 library that calculates the se of a singleton nonlinear restriction of...
2007 Oct 01
0
Clustering literature was Re: nonlinear regression
...Bayesian Information > > Criterion > > fitted.nlmeStruct(nlme) Calculate nlmeStruct Fitted > > Values > > getData.lme(nlme) Extract lme Object Data > > nlme(nlme) Nonlinear Mixed-Effects > > Models > > nlme.nlsList(nlme) NLME fit from nlsList > > Object > > nlmeControl(nlme) Control Values for nlme Fit > > nlmeObject(nlme) Fitted nlme Object > >...
2008 Jul 15
2
meaning of tests presented in anova(ols(...)) {Design package}
...(Factor+Higher Order Factors) 4 168.43 42.11 27.0 All Interactions 3 142.13 47.38 30.4 activity (Factor+Higher Order Factors) 6 536.84 89.47 57.3 All Interactions 3 142.13 47.38 30.4 Nonlinear (Factor+Higher Order Factors) 4 257.25 64.31 41.2 conc (Factor+Higher Order Factors) 4 443.02 110.75 71.0 All Interactions 3 76.74 25.58 16.4 sand (Factor+Higher Order Factors) 6 1906.29 317.71 203.6 All I...
2005 Feb 22
3
problems with nonlinear fits using nls
Hello colleagues, I am attempting to determine the nonlinear least-squares estimates of the nonlinear model parameters using nls. I have come across a common problem that R users have reported when I attempt to fit a particular 3-parameter nonlinear function to my dataset: Error in nls(r ~ tlm(a, N.fix, k, theta), data = tlm.data, start = list(a = a.st,...
2004 Jul 05
2
nonlinear regression with M estimation
Hi All, Could any one tells me if R or S has the capacity to fit nonlinear regression with Huber's M estimation? Any suggestion is appreciated. I was aware of 'rlm' in MASS library for robust linear regression and 'nls' for nonlinear least squares regression, but did not seem to be able to find robust non-linear regression function. Thanks and r...
2011 Nov 05
2
linear against nonlinear alternatives - quantile regression
Dear all, I would like to know whether any specification test for linear against nonlinear model hypothesis has been implemented in R using the quantreg package. I could read papers concerning this issue, but they haven't been implemented at R. As far as I know, we only have two specification tests in this line: anova.rq and Khmaladze.test. The first one test equality and significa...
2010 May 14
1
nonlinearity and interaction
...o and zilch elsewhere. Call the input x and the output y. I can find the relationship between x and y by fit<-lm(y~x) coef(fit) tells me the line that best fits x vs y (as shown in the plot of the 6 values of x vs the mean values of y at those values). ****Question: Suppose that the system is nonlinear such that the response to the sequence 0,2 is not the same as the response to 2, 0 -- it is not just a change of the response by the same amount. Or nonlinear in other weird ways (I don't just mean simple things like y~x^2). I am thinking that a way to characterise this might be to pretend tha...
2006 Dec 02
2
nonlinear quantile regression
Hello, I?m with a problem in using nonlinear quantile regression, the function nlrq. I want to do a quantile regression o nonlinear function in the form a*log(x)-b, the coefficients ?a? and ?b? is my objective. I try to use the command: funx <- function(x,a,b){ res <- a*log(x)-b res } Dat.nlrq <- nlrq(y ~ funx(x, a, b), data=Dat...
2005 Aug 04
2
Using nonlinear regression
Hi, I have been trying to figure out how to use the nonlinear regression to fit the cumulative lognormal distribution to a number of data points I have but I am a new R user and I cant quite decipher the notes on nonlinear regression. Any help in this regard will be greatly appreciated, my email address is mmiller at nassp.uct.ac.za
2002 Nov 09
2
Nonlinear regression and categories
Hi there: I'm trying to run a large number of nonlinear regressions on a time series dataset, where the data will be formatted something to the effect of: ObservationID,time,dependentvar I'll have a number of time and dependentvars for each observation, and I want to apply a nonlinear regression to one ObservationID at a time, and I want to have a...
2010 Feb 02
1
how to use optim() or nlm() to solve three nonlinear equations
Dear all, I just know how to solve an eaquation by using optim() or nlm(). But, now, I have three nonlinear equations, how could we use optim() or nlm() to solve  a system of nonlinear equations in R?  Thank you so much. Sincerely, Joe ___________________________________________________ 您的生活即時通 - 溝通、娛樂、生活、工作一次搞定! [[alternative HTML version deleted]]
2008 May 30
1
Alternative options: nonlinear model &autocorrelation?
Dear R community, Using nlme library I have developed a nonlinear mixed model. Incorporating an autoregressive model gives me an error that I can't allocate vector of size X. The problem is that my computer does not have enough physical memory most probably due to a large number of observations (17,000). I was wondering what alternative options I might use...
2004 Feb 04
1
Fitting nonlinear (quantile) models to linear data.
Hello. I am trying to fit an asymptotic relationship (nonlinear) to some ecological data, and am having problems. I am interested in the upper bound on the data (i.e. if there is an upper limit to 'y' across a range of 'x'). As such, I am using the nonlinear quantile regression package (nlrq) to fit a michaelis mention type model. The err...
2006 Aug 23
2
nonlinear least squares trust region fitting ?
Hello! I am running R-2.3.1-i386-1 on Slackware Linux 10.2. I am a former matlab user, moving to R. In matlab, via the cftool, I performed nonlinear curve fitting using the method "nonlinear least squares" with the "Trust-Region" algorithm and not using robust fitting. Is it possible to perform the same analysis in R? I read quite a lot of R documentation, but I could not find an alternative solution. If there is such, pleas...
2008 May 20
2
Nonlinear regression
Could someone help me on the following: SAS has DUD (Does not Use Derivatives) for nonlinear regression. Does "R" has a similar capability? I am not good at derivatives and may get my derivative wrong before feeding it to a nonlinear regression procedure. Any help would be much appreciated. Liu Hancock Forest Management NZ Tokoroa, New Zealand DDI: 07-8850387 Mobile: 021-1...
2007 May 10
2
Nonlinear constrains with optim
Dear All I am dealing at the moment with optimization problems with nonlinear constraints. Regenoud is quite apt to solve that kind of problems, but the precision of the optimal values for the parameters is sometimes far from what I need. Optim seems to be more precise, but it can only accept box-constrained optimization problems. I read in the list archives that optim can a...