Displaying 20 results from an estimated 873 matches for "nls".

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2007 Feb 21

1

Confindence interval for Levenberg-Marquardt fit

Dear all,
I would like to use the Levenberg-Marquardt algorithm for non-linear
least-squares regression using function nls.lm. Can anybody help me to
find a a way to compute confidence intervals on the fitted
parameters as it is possible for nls (using confint.nls, which does not
work for nls.lm)?
Thank you for your help
Michael

2003 Jan 17

2

nls

HI,
i have some prob when i try to use nls().
my data is 1D vector, I tried to use a polynomial function(order is 3) to
fit it.
the data series is stored in x.
the a0, a1, a2, a3 below is coefficient, which i hope i can get from
calls "nls"
> z <- nls( ~ a0 + a1 * x + a2 * x * x + a3 * x * x * x, data = x )
Error in matc...

2010 Jul 19

1

nls with some coefficients fixed

I'm using nls to fit a variety of different models. Here I use SSgompertz as
an example.
I want the ability to fix one (or more) of the coefficients that would
normally be optimised (e.g. fix b3=0.8).
Examples; based on and using data from example(SSgompertz)
#---------------------
# vanilla call to nls, no...

2009 Apr 15

2

nls factor

I want to fit the model y=a*x^b using nls; where "a" should be different for
each level of a factor.
What is the easiest way to fit it? Can i do it with nls?
I've looked the help pages and the MASS example in page 249 but the formula
is different and I don't know how to specify it for my model.
Thanks,
Manuel
[[alternat...

2006 Feb 07

1

sampling and nls formula

Hello,
I am trying to bootstrap a function that extracts the log-likelihood value and the nls coefficients from an nls object. I want to sample my dataset (pdd) with replacement and for each sampled dataset, I want to run nls and output the nls coefficients and the log-likelihood value.
Code:
x<-c(1,2,3,4,5,6,7,8,9,10)
y<-c(10,11,12,15,19,23,26,28,28,30)
pdd<-data.frame(x,y)
i&l...

2002 Feb 09

2

Language not supported

Hello
I use in /etc/X11/XF86Config XkBLayout "sr"
and have defined in KDE Srbija, srpski, ISO 8859-2
And allways got the messages:
fixme:string:GetLocaleInfoA 'IDEFAULTMACCODEPAGE' is not defined
for your language (081A).
Please define it in dlls/kernel/nls/YourLanguage.nls
and submit patch for inclusion into the next Wine release.
fixme:keyboard:X11DRV_KEYBOARD_DetectLayout Your keyboard layout
was not found! Using closest match instead (Croatian keyboard
layout) for scancode mapping.
Please define your layout in windows/x11drv/keyboard...

2008 Jun 26

3

bug in nls?

Dear all
Nobody responded to my previous post so far so I try with more offending
subject.
I just encountered a strange problem with nls formula. I tried to use nls
in cycle but I was not successful. I traced the problem to some parse
command.
Here is an example
DF<-data.frame(x=1:10, y=3*(1:10)^.5+rnorm(10))
coef(lm(log(DF[,2])~log(DF[,1])))
(Intercept) log(DF[, 1])
0.7437320 0.6831726
# this works
coef(nls(y~a*x^...

2007 May 31

1

predict.nls - gives error but only on some nls objects

Dear list,
I have encountered a problem with predict.nls (Windows XP, R.2.5.0), but I am not sure if it is a bug...
On the nls man page, an example is:
DNase1 <- subset(DNase, Run == 1)
fm2DNase1 <- nls(density ~ 1/(1 + exp((xmid - log(conc))/scal)),
data = DNase1,
start = list(xmid = 0, scal = 1))...

2006 Aug 15

2

nls convergence problem

I'm having problems getting nls to agree that convergence has occurred in a
toy problem.
nls.out never gets defined when there is an error in nls. Reaching the
maximum number of iterations is alway an error, so nls.out never gets
defined when the maximum number of iterations is reched.
>From ?nls.control:
tol: A positi...

2003 Oct 30

2

'nls' and its arguments

Dear R experts!
I'd to fit data by 'nls' with me-supplied function 'fcn'.
1) I'd like 'fcn' to accept arbitrary arguments, i.e. I defined it
as f(...) {<body>}. (Ok, that's not actually impotant).
2) Second, I would NOT like to supply every parameter in the formula.
To illustrate this, let's l...

2010 Jun 13

6

WINE is ignoring locale settings

Even on plain WINEPREFIX I am unable to get Polish-specific chars to work.
On unix (Arch x64) everytching works fine.
Wine is setting wrong codepage in registry ( in HKEY_CURRENT_USER\Software\Wine\Fonts\Codepages apears "1252,437" while it should be "1252,437")
Code:
$ locale
LANG=pl_PL.utf8
LC_CTYPE="pl_PL.utf8"
LC_NUMERIC="pl_PL.utf8"

2011 Nov 17

3

Obtaining a derivative of nls() SSlogis function

Hello, I am wondering if someone can help me. I have the following function
that I derived using nls() SSlogis. I would like to find its derivative. I
thought I had done this using deriv(), but for some reason this isn't
working out for me.
Here is the function:
asym <- 84.951
xmid <- 66.90742
scal <- -6.3
x.seq <- seq(1, 153,, 153)
nls.fn <- asym/((1+exp((xmid-x.seq)/...

2009 Feb 12

1

Using nls or nls.lm with a simulation output

We would like to fit parameters using a simulation with stochastic
processes as theoretical values. We generate a simple exemple with nls.lm
to see the logic and the problem:
First without stochasticity (it is a dummy example, the fited value is
simple the mean of a set of 10 numbers):
#Ten numbers
x <- 1:10
#Generate 10 Gaussian random number with mean=3 sd=1
simy <- rnorm(length(x), mean=3, sd=1)
#theoretical value for each...

2012 Jun 04

2

Non-linear curve fitting (nls): starting point and quality of fit

Hi all,
Like a lot of people I noticed that I get different results when I use nls
in R compared to the exponential fit in excel. A bit annoying because often
the R^2 is higher in excel but when I'm reading the different topics on this
forum I kind of understand that using R is better than excel?
(I don't really understand how the difference occurs, but I understand tha...

2010 Sep 05

0

cov.unscaled in NLS - how to define cov.scaled to make comparable to SAS proc NLIN output - and theoretically WHY are they different

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.
proc nlin data=apples outest=a;
parms b=4 d=.04 t=180;...

2011 Jun 12

1

Error in NLS example in the documentation

Hello there,
I am trying to use R function NLS to analyze my data and one of the examples
in the documentation is -
## the nls() internal cheap guess for starting values can be sufficient:
x <- -(1:100)/10
y <- 100 + 10 * exp(x / 2) + rnorm(x)/10
nlmod <- nls(y ~ Const + A * exp(B * x), trace=TRUE)
plot(x,y, main = &quo...

2017 Jul 25

0

Using nls.lm to fit a non-continuous dates range

Dear R users,
Can I fit nls.lm to a non-continuous date data. looked at previous
examples but still not able to fit the model to my data. There are 25
rows of observations as below;
df <- data.frame(Date=as.Date(rownames(df),'%m/%d/%Y'),Y=df$height)
df$days <- as.numeric(df$Date - df[1,]$Date)
head(df)...

2004 Jun 03

5

Confidence intervals for predicted values in nls

Dear all
I have tried to estimate the confidence intervals for predicted values of a
nonlinear model fitted with nls. The function predict gives the predicted
values and the lower and upper limits of the prediction, when the class of
the object is lm or glm. When the object is derived from nls, the function
predict (or predict.nls) gives only the predicted values. The se.fit and
interval aguments are just ignored...

2005 Jun 02

1

nls.control: increasing number of iterations

Hello,
I'm using the nls function and would like to increase the number of
iterations. According to the documentation as well as other postings on
R-help, I've tried to do this using the "control" argument:
nls(y ~ SSfpl(x, A, B, xmid, scal), data=my.data,
control=nls.control(maxiter=200))
but no matter...

2009 Dec 18

2

NLS-Weibull-ERROR

Hello
I was trying to estimate the weibull model using nls after putting OLS
values as the initial inputs to NLS.
I tried multiple times but still i m getting the same error of Error in
nlsModel(formula, mf, start, wts) :
singular gradient matrix at initial parameter estimates.
The Program is as below
> vel <- c(1,2,3,4,5,6,7,8,9,10,11,12,13,14)...