search for: dfoptim

Hello! I am trying to create an R optimization routine for a task that's currently being done using Excel (lots of tables, formulas, and Solver). However, otpim seems to be finding a local minimum. Example data, functions, and comparison with the solution found in Excel are below. I am not experienced in optimizations so thanks a lot for your advice! Dimitri ### 2 Inputs:

...k nmk anms neldermead ucminf optim_BFGS --------------------------------------------------- 1 0.21 0.32 0.13 0.00 0.00 3 0.52 0.63 0.50 0.00 0.00 10 0.81 0.91 0.87 0.00 0.00 Solvers: nmk = dfoptim::nmk, anms = pracma::anms [both Nelder-Mead codes] neldermead = nloptr::neldermead, ucminf = ucminf::ucminf, optim_BFGS = optim with method "BFGS" Read the table as follows: `nmk` will be successful in 21% of the trials, while for example `optim` will never come close t...

Hallo together, I am trying to use the nmkb() optimizer and I have problems using the function, as it causes the following error message Fehler (error)* in while (nf < maxfeval & restarts < restarts.max & dist > ftol & : Fehlender Wert (missing value)* , wo (where)* TRUE/FALSE n?tig ist (is required)* *translation Do I need to adjust the control ?

...1975. It still works well as a first-try method for optimization, but generally is less efficient than gradient based methods, in particular because it does not have a good way to know it is finished. As a derivative-free method, it is "not too bad", particularly in the nmk version in the dfoptim package. Indeed, I wish this version were put in optim() as the default, since it can deal with bounds constraints, though slightly less generally and less well than bobyqa or some other methods, and there are a couple of minor details it handles better than N-M in optim() that give it better perfo...

Hi All, I have a situation where I want an 'if' variable to be parameterized. It's entirely possible that the way I'm trying to do this is wrong, especially given the error message I get that indicates I can't do this using an 'if' statement. Essentially, I have data where I think a relationship enters when a variable (here Pwd) is below some value (z). I don't

Hello, I am attempting to use optim under the default Nelder-Mead algorithm for model fitting, minimizing a Chi^2 statistic whose value is determined by a .C call to an external shared library compiled from C & C++ code. My problem has been that the R session will immediately crash upon starting the simplex run, without it taking a single step. This is strange, as the .C call itself works,

Dear R users I am trying to use OPTIMX(OPTIM) for nonlinear optimization. There is no error in my code but the results are so weird (see below). When I ran via OPTIM, the results are that Initial values are that theta0 = 0.6 1.6 0.6 1.6 0.7. (In fact true vales are 0.5,1.0,0.8,1.2, 0.6.) -------------------------------------------------------------------------------------------- >

Hi, I've got a matrix, Z, of values representing (as it happens) optical power at each pixel location. Since I know in advance I've got a single, convex peak, I would like to do a 2D parabolic fit of the form Z = poly((x+y),2) where x and y are the x,y coordinates of each pixel (or equivalently, the row, column numbers). Is there an R function that lets me easily implement that?

Hi all, Many thank in advance for helping me.? I tried to fit Expectation Maximization algorithm for mixture data. I must used one of numerical method to maximize my function. I built my code but I do not know how to make the optim function run over a different value of the parameters.? That is, For E-step I need to get the value of mixture weights based on the current (initial) values of

Hello, I am new to R and I am trying to estimate a discrete model with three choices. I am stuck at a point and cannot find a solution. I have probability functions for occurrence of these choices, and then I build the likelihood functions associated to these choices and finally I build the general log-likelihood function. There are four parameters in the model, three of them are associated to