similar to: starting point for non linear fitting

Displaying 20 results from an estimated 20000 matches similar to: "starting point for non linear fitting"

2003 Apr 19
1
nls, gnls, starting values, and covariance matrix
Dear R-Help, I'm trying to fit a model of the following form using gnls. I've fitted it using nlsList with the following syntax: nlsList(Y~log(exp(a0-a1*X)+exp(b0-b1*X))|K,start=list (a0=6,a1=0.2,b0=4.5,b1=0.001),data=data.frame(Y=y,X=X,K=k))) which works just fine: <snip> Coefficients: a0 a1 b0 b1 1 5.459381 0.5006811 5.137458 -0.0040548687
2006 Sep 14
1
EBAM ERROR
Dear RUsers, I am new to R. I am learning how to use R. I am a PC user and run R on windows. I would appreciate if some one could guide me on a few questions I have: 1) I have 4 cel files (2 replicates for NORM and Disease resp). I have been able to run siggenes on this dataset where I have 4 labels in the class file groupsnhi.cl op-> (0,0,1,1) and my data has been read into datrmanhi after
2015 Sep 05
3
[PATCH] mips/setjmp.S don't save and restore float point registers
Klibc FTBFS with '-mno-odd-spreg' on mips32(el) platforms, As it try to save/restore odd-number FPR. Indeed no other architectures save/restore FPR at all. It shouldn't be needed. --- usr/klibc/arch/mips/setjmp.S | 24 ------------------------ 1 file changed, 24 deletions(-) diff --git a/usr/klibc/arch/mips/setjmp.S b/usr/klibc/arch/mips/setjmp.S index 68eed19..21e4115 100644 ---
2006 Sep 28
1
Nonlinear fitting - reparametrization help
Hi, I am trying to fit a function of the form: y = A0 + A1 * exp( -0.5* ( (X - Mu1) / Sigma1 )^2 ) - A2 * exp ( -0.5* ( (X-Mu2)/Sigma2 )^2 ) i.e. a mean term (A0) + a difference between two gaussians. The constraints are A1,A2 >0, Sigma1,Sigma2>0, and usually Sigma2>Sigma1. The plot looks like a "Mexican Hat". I had trouble (poor fits) fitting this function to toy data
2011 Oct 06
1
Fitting parabolic function to data
Dear R users and experts, I want to fit a shifted parabolic function with the following functional form to my data: f(x)=a0*(x+a1)^2+a2 (a0, a1 and a2 are scaling factors.) What is standard approach to do this in R? I tried the "lm" function in R but I got problems getting the above functional form. Any help is welcome :) . Greetings, Henri
2010 Jul 29
1
Linear Interpolation question
Hi R experts, I have the following timeseries data: #example data structure a <- c(NA,1,NA,5,NA,NA,NA,10,NA,NA) c <- c(1:10) df <- data.frame(timestamp=a, sequence=c) print(df) where i would like to linearly interpolate between the points 1,5, and 10 in 'timestamp'. Original timestamps should not be modified. Here the code I use to run the interpolation (so far): # linear
2008 Aug 14
1
non-linear regression problem
I need to do a non-linear regression in the form of Y = a0 + a1 * arctan(a2 * x) + error. A data sample (X,Y) is available, but I can't remember how to run this sort of regression through R so that I get a value for a0, a1 and a2. Can someone please give me a hint? Thank you in advance.
2023 Dec 09
1
Linear model and approx function
Dear all; I have a dataframe with several columns. The columns are the elevation, volume and the area of the cells (which were placed inside a polygon). I have extracted them from DEM raster to calculate the volume under polygon and the elevation for a specific volume of the reservoir. > head(x6,2) Elevation Vol Area V_sum A_sum 1 2145 13990.38 85.83053 13990.38
2008 Feb 13
3
isolinux not booting - old 486 with SCSI CD writer
I am trying to install Debian Linux on an an old Intel Classic R+ computer that uses an internal Yamaha SCSI CD writer model CRW8424S connected to an Adaptec ISA SCSI card (I think its a 1542CP). The CD writer is is the only device connected to the SCSI card. The computer has one hard drive connected to the on-board IDE interface, a 1.44MB 3 1/2 inch floppy and a 1.2MB 5 1/4 inch floppy. The hard
2001 Oct 05
1
nls() fit to a lorentzian - can I specify partials?
First, thanks to all who helped me with my question about rescaling axes on the fly. Using unlist() and range() to set the axis ranges in advance worked well. I've since plotted about 300 datasets with relative ease. Now I'm trying to fit a lossy oscillator resonance to (the square root of) a lorentzian (testframe$y is oscillator amplitude, testframe$x is drive frequency): lorentz
2008 Jun 14
1
restricted coefficient and factor in linear regression.
Hi, my data set is data.frame(id, yr, y, l, e, k). I would like to estimate Lee and Schmidts (1993, OUP) model in R. My colleague wrote SAS code as follows: ** procedures for creating dummy variables are omitted ** ** di# and dt# are dummy variables for industry and time ** data a2; merge a1 a2 a; by id yr; proc sysnlin maxit=100 outest=beta2; endogenous y; exogenous l e k
2009 Aug 07
1
Bug in nlm, found using sem; failure in several flavors (PR#13883)
This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --1660387551-150661043-1249684349=:2997 Content-Type: TEXT/PLAIN; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Hi Jeff, =09As mentioned in my message, I *did* replicate on another platform.=20 One platform was
2005 Mar 28
1
logcheck errors after logrotate runs
--nextPart2699335.H7BBWTdPIb Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Hello :) After upgrading recently from Woody to Sarge (which went fairly well) I now= =20 have trouble with logcheck. I have been unable to track down a solution. Logcheck runs perfectly through the week until Sunday when logrotate does
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 that there is a
2008 Jun 09
1
nonlinear fitting on many voxels
After many months, I am now banging my head against the wall because I can't find a solution to this seemingly trivial problem.&nbsp; Any help would be appreciated: I am trying to apply a nonlinear fitting routine to a 3D MR image on a voxel-by-voxel basis.&nbsp; I've tested the routine using simulated data and things went well.&nbsp; As for the real data, the fitting routine
2006 Sep 14
0
Help On EBAM
Dear RUsers, I am new to R. I am learning how to use R. I am a PC user and run R on windows. I would appreciate if some one could guide me on a few questions I have: 1) I have 4 cel files (2 replicates for NORM and Disease resp). I have been able to run siggenes on this dataset where I have 4 labels in the class file groupsnhi.cl op-> (0,0,1,1) and my data has been read into datrmanhi after
2005 Feb 15
3
using poly in a linear regression in the presence of NA f ails (despite subsetting them out)
This smells like a bug to me. The error is triggered by the line: variables <- eval(predvars, data, env) inside model.frame.default(). At that point, na.action has not been applied, so poly() ended being called on data that still contains missing values. The qr() that issued the error is for generating the orthogonal basis when evaluating poly(), not for fitting the linear model itself.
2005 Feb 15
3
using poly in a linear regression in the presence of NA f ails (despite subsetting them out)
This smells like a bug to me. The error is triggered by the line: variables <- eval(predvars, data, env) inside model.frame.default(). At that point, na.action has not been applied, so poly() ended being called on data that still contains missing values. The qr() that issued the error is for generating the orthogonal basis when evaluating poly(), not for fitting the linear model itself.
2007 Aug 15
1
Polynomial fitting
Hi everybody! I'm looking some way to do in R a polynomial fit, say like polyfit function of Octave/MATLAB. For who don't know, c = polyfit(x,y,m) finds the coefficients of a polynomial p(x) of degree m that fits the data, p(x[i]) to y[i], in a least squares sense. The result c is a vector of length m+1 containing the polynomial coefficients in descending powers: p(x) = c[1]*x^n +
2014 Mar 11
4
[PATCH] add mips64 support
From: Dejan Latinovic <Dejan.Latinovic at imgtec.com> --- usr/include/arch/mips64/klibc/archconfig.h | 3 + usr/include/arch/mips64/klibc/archsetjmp.h | 39 ++++++ usr/include/arch/mips64/machine/asm.h | 76 ++++++++++ usr/include/fcntl.h | 2 +- usr/include/sys/md.h | 1 + usr/include/sys/resource.h | 4 +-