search for: mcs39

Displaying 2 results from an estimated 2 matches for "mcs39".

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2006 Sep 30
1
Gradient problem in nlm
Hello everyone! I am having some trouble supplying the gradient function to nlm in R for windows version 2.2.1. What follows are the R-code I use: fredcs39<-function(a1,b1,b2,x){return(a1+exp(b1+b2*x))} loglikcs39<-function(theta,len){ value<-sum(mcs39[1:len]*fredcs39(theta[1],theta[2],theta[3],c(8:(7+len))) - pcs39[1:len] * log(fredcs39(theta[1],theta[2],theta[3],c(8:(7+len))))) a1<-theta[1]; b1<-theta[2]; b2<-theta[3] df.a1<-sum(-mcs39[1:len] + pcs39[1:len]/(a1+exp(b1+b2*c(8:(7+len))))) df.b1<-sum( -mcs39[1:len] * exp(b1+b2*c(8:(...
2006 Sep 26
1
warning message in nlm
Dear R-users, I am trying to find the MLEs for a loglikelihood function (loglikcs39) and tried using both optim and nlm. fredcs39<-function(b1,b2,x){return(exp(b1+b2*x))} loglikcs39<-function(theta,len){ sum(mcs39[1:len]*fredcs39(theta[1],theta[2],c(8:(7+len))) - pcs39[1:len] * log(fredcs39(theta[1],theta[2],c(8:(7+len))))) } theta.start<-c(0.1,0.1) 1. The output from using optim is as follow -------------------------------------------------------------- optcs39<-optim(theta.start,loglikcs39,len=120...