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I have an error for a simple optimization problem. Is there anyone knowing about this error? lambda1=-9 lambda2=-6 L<-function(a){ s2i2f<-(exp(-lambda1*(250^a)-lambda2*(275^a-250^a)) -exp(-lambda1*(250^a)-lambda2*(300^a-250^a))) logl<-log(s2i2f) return(-logl)} optim(1,L) Error in optim(1, L) : function cannot be evaluated at initial parameters Thank you in advance -- View this

...ency (to somehow measure effective model complexity) Both I would extract from the MCMC-trace. Sounds simple? It possibly is - just not for me. I compared several MCMC algorithms implemented in R, from Win/OpenBUGS over MCMCmetrop1R (MCMCpack; my current favourite) and metrop (mcmc) to gibbs and rwmetrop (LearnBayes) and gibbs_met (gibbs.met). These implementations differ dramatically in efficiency (MCMCmetrop1R was over 20 times faster than gibbs_met). Since my functions can be complex (mainly ODEs, complex environmental models programmed in Fortran or C to be called by the system-function), I...