Displaying 20 results from an estimated 6000 matches similar to: "optimization and gradient"
2008 May 27
4
package functions documentation
Dear all,
I am currently creating a package and writing the documention files for
some functions (the main functions). When using R CMD check myPackage, I
get a warning message indicating that some of my functions are not
documented. How can I get rid of this problem? Of course, I don't want
to document every function in the package...
Thanks for your help.
--
David Ardia
H-building, room
2008 Apr 25
1
No rule to make target 'R/Copy'
Dear all,
I am currently building a package with C code (in scr folder).
Everything was ok, but now, I get the following error message when
compiling the package using R CMD INSTALL:
make[2]: *** No rule to make target 'R/Copy', needed in [...]
What does that mean? I can still compile other packages containing C
code, but not that one. No 00UNLOCK directory has been created . I am on
2008 Apr 24
1
Passing Inf from R to C using .C("myLibC"...
Dear all,
How can I pass '-Inf' and 'Inf' values from R to C code using the
function '.C(...)'. When running my code, I get an error since C does
not recognize -Inf and Inf values. Of course, I could use instead a very
low (or high) number, but I was wondering whether a more elegant
solution exists. Thanks for your help.
--
David Ardia
H-building, room 11-26
1999 Dec 01
2
nlmin
I'm a very recent user of R. I have been adapting my Splus programmes
and I found only one (important) problem. There exists no function
"nlmin" in R and its substitute, "nlm", does not work well with my kind
of problems, sometimes no achieving convergence, other tines
"converging" to impossible values. My models are highly nonlinear and
are to be estimated by
2009 Jan 26
0
AdMit version 1-01.01
Dear all,
The new version of AdMit (version 1.01-01) is now available from CRAN.
SUMMARY
The package provides functions to perform the fitting of an adaptive
mixture of Student-t distributions to a target density through its
kernel function. The mixture approximation can then be used as the importance
density in importance sampling or as the candidate density in the
Metropolis-Hastings
2009 Jan 26
0
AdMit version 1-01.01
Dear all,
The new version of AdMit (version 1.01-01) is now available from CRAN.
SUMMARY
The package provides functions to perform the fitting of an adaptive
mixture of Student-t distributions to a target density through its
kernel function. The mixture approximation can then be used as the importance
density in importance sampling or as the candidate density in the
Metropolis-Hastings
2012 Sep 26
2
non-differentiable evaluation points in nlminb(), follow-up of PR#15052
This is a follow-up question for PR#15052
<http://bugs.r-project.org/bugzilla3/show_bug.cgi?id=15052>
There is another thing I would like to discuss wrt how nlminb() should
proceed with NAs. The question is: What would be a successful way to
deal with an evaluation point of the objective function where the
gradient and the hessian are not well defined?
If the gradient and the hessian both
2009 Nov 29
1
optim or nlminb for minimization, which to believe?
I have constructed the function mml2 (below) based on the likelihood function described in the minimal latex I have pasted below for anyone who wants to look at it. This function finds parameter estimates for a basic Rasch (IRT) model. Using the function without the gradient, using either nlminb or optim returns the correct parameter estimates and, in the case of optim, the correct standard
2008 Jun 23
0
AdMit 1.00-02
'AdMit' 1.00-02 is a contributed R package which provides functions to
perform the fitting of an
adaptive mixture of Student-t distributions to a target density through
its kernel function.
The mixture approximation can then be used as the importance density
in importance sampling or as the candidate density in the
Metropolis-Hastings algorithm to
obtain quantities of interest for the
2009 Mar 03
2
R - MATLAB apply like function
Dear all,
I very often use the R function "apply", for speedup purposes. I am now also using MATLAB, and would like to use the same kind of function.
I have already asked MATLAB people, and the answer is : "vectorize"... but of course, this is not always possible. So, instead of using
a FOR loop all the time, I tried using the bsxfun. So you R people, who might also use MATLAB,
2004 Feb 24
2
convergence in polr
Hello splus-users, I am trying to fit a regression model for an ordered
response factor. So I am using the function polr in library(MASS). My data
is a matrix of 1665 rows and 63 columns (one of the column is the dependent
variable). The code I use is polr(as.ordered(q23p)~.,data=newdatap)
but I am getting the following warning message singularity encountered in:
nlminb.1(temp, p, liv, lv,
2019 Jan 28
8
nlminb with constraints failing on some platforms
I've noticed unstable behavior of nlminb on some Linux systems. The problem can be reproduced by compiling R-3.5.2 using gcc-8.2 and running the following snippet:
f <- function(x) sum( log(diff(x)^2+.01) + (x[1]-1)^2 )
opt <- nlminb(rep(0, 10), f, lower=-1, upper=3)
xhat <- rep(1, 10)
abs( opt$objective - f(xhat) ) < 1e-4 ## Must be TRUE
The example works perfectly when
2006 Apr 20
2
nlminb( ) : one compartment open PK model
All,
I have been able to successfully use the optim( ) function with
"L-BFGS-B" to find reasonable parameters for a one-compartment
open pharmacokinetic model. My loss function in this case was
squared error, and I made no assumptions about the distribution
of the plasma values. The model appeared to fit pretty well.
Out of curiosity, I decided to try to use nlminb( ) applied to
a
2005 Dec 04
1
Understanding nonlinear optimization and Rosenbrock's banana valley function?
GENERAL REFERENCE ON NONLINEAR OPTIMIZATION?
What are your favorite references on nonlinear optimization? I like
Bates and Watts (1988) Nonlinear Regression Analysis and Its
Applications (Wiley), especially for its key insights regarding
parameter effects vs. intrinsic curvature. Before I spent time and
money on several of the refences cited on the help pages for "optim",
2005 Dec 14
2
suggestions for nls error: false convergence
Hi,
I'm trying to fit some data using a logistic function defined as
y ~ a * (1+m*exp(-x/tau)) / (1+n*exp(-x/tau)
My data is below:
x <- 1:100
y <- c(0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,1,1,1,2,2,2,2,2,3,4,4,4,5,
5,5,5,6,6,6,6,6,8,8,9,9,10,13,14,16,19,21,
24,28,33,40,42,44,50,54,69,70,93,96,110,127,127,141,157,169,
2011 Jan 21
3
nlminb doesn't converge and produce a warning
Hi Everybody,
My problem is that nlminb doesn't converge, in minimising a logLikelihood
function, with 31*6 parameters(2 weibull parameters+29 regressors repeated 6
times).
I use nlminb like this :
res1<-nlminb(vect, V, lower=c(rep(0.01, 12), rep(0.01, 3), rep(-Inf, n-15)),
upper=c(rep(Inf, 12), rep(0.99, 3), rep(Inf, n-15)), control =
list(maxit=1000) )
and that's the result :
2019 Feb 01
3
nlminb with constraints failing on some platforms
Hello,
R 3.5.2 on ubuntu 18.04. sessionInfo() at the end.
Works with me, same results, cannot reproduce the error.
f <- function(x) sum( log(diff(x)^2+.01) + (x[1]-1)^2 )
opt <- nlminb(rep(0, 10), f, lower=-1, upper=3)
str(opt)
xhat <- rep(1, 10)
all.equal(opt$par, xhat, tol=0) # good: 5.53 e-7
#[1] "Mean relative difference: 5.534757e-07"
all.equal(opt$objective,
2006 Mar 16
1
lme4/Matrix: Call to .Call("mer_update_y"...) and LMEoptimize gives unexpected side effect...
Dear all
I want to compute Monte Carlo p-values in lmer-models based on sampled data sets. To speed up calculations, I've tried to use internal functions from the Matrix package (as suggested ealier on the list by Doug Bates).
So I did:
fm2 <- lmer(resistance ~ ET + position + (1|Grp), Semiconductor,method='ML')
simdata<-simulate(fm2,nsim=1)
ynew <- simdata[,1]
mer
2011 Aug 16
2
Calibrating the risk free interest rate using nlminb
Dear R-users
I am trying to find a value for the risk free rate minimizing the difference
between a BS call value with impl. volatilities minus the market price of a
call (assuming this is just the average bid ask price)
Here is my data:
http://r.789695.n4.nabble.com/file/n3747509/S%26P_500_calls%2C_jan-jun_2010.csv
S%26P_500_calls%2C_jan-jun_2010.csv
S0 <- 1136.03
q <- 0.02145608
S0
1999 Jan 21
2
nlm question
Hello again
Is there any way (or an alternative non-linear minimiser) that arguments
to the function called in nlm can be passed in version 0.62.4? Like (I
believe) nlmin in a well known other program or optimise in R. Do we use
global variables? Shurely not!
\John
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