Hi, I've made a selfStart function for use with gnls and the following piece of code works nicely:
check1 <- gnls(y ~ spot.shape.fct(xcord, ycord, background, spotintensity, rho, sigma, delta, mux, muy), start=getInitial(y ~ spot.shape.fct(xcord, ycord, background, spotintensity, rho, sigma, delta, mux, muy), data=claus), data=claus ) spot.shape.fct is the selfStart function and I later want to include a correlation term which is why I'm using gnls instead of nls. I want to get rid of the start= option, but I keep getting the following error message: Error in nls(formula = y ~ spot.shape.fct(xcord, ycord, background, spotintensity, : number of iterations exceeded maximum of 50 >From the help page and the glns code I can see that the initial start values are improved by estimating the parameters in a model without the correlation structures that are possible with gnls. This is quite reasonable and will quite likely improve the convergence succes and time once a correlation is introduced. Obviously the call to nls does not converge before the standard 50 iterations specified in nls.control so I was wondering if it is possible to pass nls.control information on to nls when calling gnls? Several work-around exists: * Write a better initial function to get more precise starting values, i.e., fewer iterations needed for nls. * Make a new function my.own.gnls where nls.control(maxiter=100) is set in the call to nls. Maybe it would even be a good idea to pass nlsMaxIter from gnlsControl on to the initial call to nls? As far as I can see from the code it is only used in maximization after the call to get the starting value. Happy R'ing Claus -- ***************************************** Claus Thorn Ekstrøm <[EMAIL PROTECTED]> Dept of Mathematics and Physics, KVL Thorvaldsensvej 40 DK-1871 Frederiksberg C Denmark Phone:[+45] 3528 2341 Fax: [+45] 3528 2350 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help