[R] Help for numericDeriv function

Hi, I am stuck on something for a couple days, I am almost about to give up. This looks simple, but I can't figure out. I hope I can get some help here. I am trying to do some symbolic and numerical derivations. Let me explain the problem. Let's say, I have a matrix as follows: load -

Re: [R] Help for numericDeriv function

I missed a couple line of codes in the previous e-mail. Here is whole code again: load - matrix(c(3,0,1,4,1,3),nrow=3,ncol=2,byrow=TRUE) l - matrix(nrow=nrow(load),ncol=ncol(load)) for(i in 1:nrow(load)) { for(j in 1:ncol(load)) { l[i,j]=paste(l,i,j,sep=)}} for(i in 1:nrow(load)){ for(j in

Re: [R] Estimating IRT models by using nlme() function

Thanks for your suggestion, Dimitris. I know (and use) all of these R packages for IRT (I am actually writer of one of them, EstCRM). I also use specialized commercial software such as BILOG and MULTILOG. My goal is to be able to estimate IRT model parameters in a nonlinear mixed effects