Displaying 20 results from an estimated 1000 matches similar to: "nls"
2003 Jan 30
2
Regarding R
Hi,
I am a grad student at the university of Louisiana at Lafayette. I have a
question. I have an equation with 3 unknowns. f= P/ (r+p) pow(B). I have values
of f for different r's. Can i use R to find the P,p,B values which are
constants. The equation is Manderbolts equation.
Thanks and regards,
Sai Charan Komanduru
Research Assistant, CACS
ULL
2003 Feb 19
1
nls
Hi,
I am using nls library
df <- read.table("data.txt", header=T);
library(nls);
fm <- nls(y ~ a*(x+d)^(-b), df, start=list(a=max(df->y,na.rm=T)/2,b=1,d=0));
coef(fm);
q();
When i am using the above routine i am getting the following error
Error in nlsModel(formula, mf, start) : singular gradient matrix at initial
parameter estimates
Can some one help me in this.
2008 May 06
2
NLS plinear question
Hi All.
I've run into a problem with the plinear algorithm in nls that is confusing
me.
Assume the following reaction time data over 15 trials for a single unit.
Trials are coded from 0-14 so that the intercept represents reaction time in
the first trial.
trl RT
0 1132.0
1 630.5
2 1371.5
3 704.0
4 488.5
5 575.5
6 613.0
7 824.5
8 509.0
9
2008 Oct 02
1
nls with plinear and function on RHS
Dear R gurus,
As part of finding initial values for a much more complicated fit I want to
fit a function of the form y ~ a + bx + cx^d to fairly "noisy" data and have
hit some problems.
To demonstrate the specific R-related problem, here is an idealised data
set, smaller and better fitting than reality:
# idealised data set
aDF <- data.frame( x= c(1.80, 9.27, 6.48, 2.61, 9.86,
2003 Jan 30
0
Re: Regarding Installation
Its possible to corrupt the binary if you actually open it in a browser,
and the browser tries to display it, and then you save it.
Have you tried right-clicking on the link to download it?
Robert.
On Thu, 30 Jan 2003, saicharan komanduru wrote:
> Hi,
> I copied the binary setup file for windows. I tried
> to install but it says the binary is corrupted. I
> tried getting the files
2010 Apr 15
2
using nls for gamma distribution (a,b,d)
Dear all
i want to estimated the parameter of the gamma density(a,b,d)
f(x) = (1/gamma(b)*(a^b)) * ((x-d)^(b-1)) * exp{-(x-d)/a)} for x>d
f(x) = Age specific fertility rate
x = age
when i run this in R by usling nls()
gamma.asfr <- formula(asfr ~ (((age-d)^(b-1))/((gamma(b))*(a^b)))*
exp(-((age-d)/a)))
gamma.asfr1 <- nls(gamma.asfr, data= asfr.aus, start = list(b = 28, a = 1,
d= 0.5),
2003 Jan 30
3
Regarding Installation of R
Hi,
I am trying to install R on Windows. I copied the set
up binary. But it is corrupted on all the mirror
sites. Please let know an alternative for getting the
software.
Thanks,
Sai
2012 Jan 30
1
Problem in Fitting model equation in "nls" function
Dear R users,
I am struggling to fit expo-linear equation to my data using "nls" function. I am always getting error message as i highlighted below in yellow color:
### Theexpo-linear equation which i am interested to fit my data:
response_variable = (c/r)*log(1+exp(r*(Day-tt))), where "Day" is time-variable
## my response variable
rl <-
2012 Jan 31
4
problem in fitting model in NLS function
Dear R users,
I am struggling to fit expo-linear equation to my data using "nls" function. I am always getting error message as i highlighted below in yellow color:
Theexpo-linear equation which i am interested to fit my data:
response_variable = (c/r)*log(1+exp(r*(Day-tt))), where "Day" is time-variable
my response variable
rl <-
2005 Jun 21
2
nls(): Levenberg-Marquardt, Gauss-Newton, plinear - PI curve fitting
Hello,
i have a problem with the function nls().
This are my data in "k":
V1 V2
[1,] 0 0.367
[2,] 85 0.296
[3,] 122 0.260
[4,] 192 0.244
[5,] 275 0.175
[6,] 421 0.140
[7,] 603 0.093
[8,] 831 0.068
[9,] 1140 0.043
With the nls()-function i want to fit following formula whereas a,b, and c
are variables: y~1/(a*x^2+b*x+c)
With the standardalgorithm
2006 Jan 08
1
confint/nls
I have found some "issues" (bugs?) with nls confidence intervals ...
some with the relatively new "port" algorithm, others more general
(but possibly in the "well, don't do that" category). I have
corresponded some with Prof. Ripley about them, but I thought I
would just report how far I've gotten in case anyone else has
thoughts. (I'm finding the code
2012 Aug 23
1
NLS bi exponential Fit
Hi everyone,
I'm trying to perform a bi exponential Fit with the package NLS. the
plinear algorithm seems to be a good choice
see:
p<-3000
q<-1000
a<--0.03
b<--0.02
t<-seq(0:144);t
y<-p*exp(a*t) + q*exp(b*t)+rnorm(t,sd=0.3*(p*
exp(a*t) + q*exp(b*t)))
fittA <- nls(y~cbind(exp(a*t), exp(b*t)),
algorithm="plinear",start=list(a=-.1, b=-0.2), data=list(y=y, t=t),
2010 Oct 13
2
Using NLS with a Kappa function
Hi Everyone,
I am trying to use NLS to fit a dataset using a Kappa function, but I am
having problems. Depending on the start values that I provide, I get
either:
Error in numericDeriv(form[[3L]], names(ind), env) :
Missing value or an infinity produced when evaluating the model
Or
Error in nls(FldFatRate ~ funct3(MeanDepth_m, h, k, z, a), data = data1, :
singular gradient
I think these
2008 Jul 08
2
nls and "plinear" algorithm
hello all
i havnt had a chance to read through the references provided for the
"nls" function (since the libraries are closed now).
can anyone shed some light on how the "plinear" algorithm works? also,
how are the fitted values obtained? also, WHAT DOES THE ".lin" below
REPRESENT?
thanking you in advance
######################################
i have a quick
2007 Dec 24
1
curve fitting problem
I'm trying to fit a function y=k*l^(m*x) to some data points, with reasonable starting value estimates (I think). I keep getting "singular matrix 'a' in solve".
This is the code:
ox <- c(-600,-300,-200,1,100,200)
ir <- c(1,2.5,4,9,14,20)
model <- nls(ir ~ k*l^(m*ox),start=list(k=10,l=3,m=0.004),algorithm="plinear")
summary(model)
plot(ox,ir)
testox <-
2007 Apr 16
1
nls with algorithm = "port", starting values
The documentation for nls says the following about the starting values:
start: a named list or named numeric vector of starting estimates.
Since R 2.4.0, when 'start' is missing, a very cheap guess
for 'start' is tried (if 'algorithm != "plinear"').
It may be a good idea to document that when algorithm = "port", if start
is a named
2008 Jul 09
2
Port package
Hi
When I type:
> ?nls
I come across this section:
algorithm: character string specifying the algorithm to use. The
default algorithm is a Gauss-Newton algorithm. Other
possible values are '"plinear"' for the Golub-Pereyra
algorithm for partially linear least-squares models and
'"port"' for the 'nl2sol'
2006 Sep 15
1
Formula aruguments with NLS and model.frame()
I could use some help understanding how nls parses the formula argument
to a model.frame and estimates the model. I am trying to utilize the
functionality of the nls formula argument to modify garchFit() to handle
other variables in the mean equation besides just an arma(u,v)
specification.
My nonlinear model is
y<-nls(t~a*sin(w*2*pi/365*id+p)+b*id+int,data=t1,
2004 Jul 18
2
bootstrap and nls
Hi,
I am trying to bootstrap the difference between each parameters among two non linear regression (distributed loss model) as
following:
# data.frame
> Raies[1:10,]
Tps SolA Solb
1 0 32.97 35.92
2 0 32.01 31.35
3 1 21.73 22.03
4 1 23.73 18.53
5 2 19.68 18.28
6 2 18.56 16.79
7 3 18.79 15.61
8 3 17.60 13.43
9 4 14.83 12.76
10 4 17.33 14.91
etc...
# non
2011 Jun 15
4
Problems with nls
I'm trying to fit the Bass Diffusion Model using the nls function in R but
I'm running into a strange problem. The model has either two or three
parameters, depending on how it's parameterized, p (coefficient of
innovation), q (coefficient of immitation), and sometimes m (maximum market
share). Regardless of how I parameterize the model I get an error saying
that the step factor has