# invalid "mode" of argument optimize

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## invalid "mode" of argument optimize

 Hello everybody, i have the following function, which i want to solve for b i=1,..,n,  and n is the length of t and t is the last element of t, if you do cumsum() before. (t_n*exp(-b*t_n)*sum_{i=1}^{n} f_i) / (1-exp(-b*t_n)) - (sum_{i=1}^{n} (f_i*(t_i*exp(-b*t_i)-t_{i-1}*exp(-b*t_{i-1}))) / (exp(-b*t_{i-1})-exp(-b*t_i)) )  = 0 i implemented this function in the following way ll2<-function(b,f,t) {   t<-cumsum(t)   tn<-t[length(t)]   i<-seq(along=f)   s1<-tn*exp(-b*tn)*sum(f[i])   s2<-(1-exp(-b*tn))   i[length(i)+1]<-0   i<-sort(i)   f[length(f)+1]<-1   t[length(t)+1]<-0   t<-sort(t)   s3<-f[2]*(t[2]*exp(-b*t[2])-t[1]*exp(-b*t[1]))   s4<-exp(-b*t[1])-exp(-b*t[2])   i<-i[3:length(i)]   s5<-sum(f[i]*(t[i]*exp(-b*t[i])-t[i-1]*exp(-b*t[i-1])))   s6<-sum(exp(-b*t[i-1])-exp(-b*t[i]))   (s1/s2)-((s3/s4)+(s5/s6)) } # i have the given data f=c(1,1,1) t=c(320,14390,9000) # now i wanted to use optimize() to get the minimum of ll2() with the given data xmin<-optimize(ll2,c(0,10000),tol=0.001,f=f,t=t) and i got always the error "invalid "mode" of argument  optimize", but i don't now what is really wrong? Or is there any mistake in my implementation of the function? best regards Andreas ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide! http://www.R-project.org/posting-guide.html