yes, log of negative number is undefined and R also do the same and
produces NaNs. Here I want to reject the value of exp(-alpha*d^(-beta))
when greater than 1, and want to run the loop otherwise.
Thanks
On Tue, Nov 29, 2011 at 6:48 PM, Sarah Goslee <sarah.gos...@gmail.com>wrote:
> > Here p[i] <- 1 - exp(-alpha*d^(-beta))> so, log(p[i]) produces NaNs
> when exp(-alpha*d^(-beta)) is greater than 1.> How can I remove it.After
> generating the out put we can omit it, but the> problem is different.
>
> Wait... you're complaining that you can't take the natural log of a
> negative
> number in R?
>
> You can't do that anywhere. What do you expect to happen? The log of a
> negative number IS NaN.
>
> Sarah
> On Tue, Nov 29, 2011 at 6:28 PM, Gyanendra Pokharel
> <gyanendra.pokha...@gmail.com> wrote:
> > I have following code:
> > loglikelihood <- function(alpha,beta= 0.1){
> > loglh<-0
> > d<-0
> > p<-0
> > k<-NULL
> > data<-read.table("epidemic.txt",header = TRUE)
> > attach(data, warn.conflicts = F)
> > k <-which(inftime==1)
> > d <- (sqrt((x-x[k])^2+(y-y[k])^2))^(-beta)
> > p<-1 - exp(-alpha*d)
> > for(i in 1:100){
> > if(i!=k){
> > if(inftime[i]==0){
> > loglh<-loglh +log(1-p[i])
> > }
> > if(inftime[i]==2){
> > loglh<-loglh + log(p[i])
> > }
> > }
> > }
> > return(loglh)
> > }
> > Here p[i] <- 1 - exp(-alpha*d^(-beta))
> > so, log(p[i]) produces NaNs when exp(-alpha*d^(-beta)) is greater than
> 1.
> > How can I remove it.After generating the out put we can omit it, but the
> > problem is different.
> >
> > On Tue, Nov 29, 2011 at 5:22 PM, Gyanendra Pokharel <
> > gyanendra.pokha...@gmail.com> wrote:
> >
> >> No, that,s not a problem Michael,
> >> I have following code:
> >> loglikelihood <- function(alpha,beta= 0.1){
> >> loglh<-0
> >> d<-0
> >> p<-0
> >> k<-NULL
> >> data<-read.table("epidemic.txt",header = TRUE)
> >> attach(data, warn.conflicts = F)
> >> k <-which(inftime==1)
> >> d <- (sqrt((x-x[k])^2+(y-y[k])^2))^(-beta)
> >> p<-1 - exp(-alpha*d)
> >> for(i in 1:100){
> >> if(i!=k){
> >> if(inftime[i]==0){
> >> loglh<-loglh +log(1-p[i])
> >> }
> >> if(inftime[i]==2){
> >> loglh<-loglh + log(p[i])
> >> }
> >> }
> >> }
> >> return(loglh)
> >> }
> >> Here p[i] <- 1 - exp(-alpha*d^(-beta))
> >> so, log(p[i]) produces NaNs when exp(-alpha*d^(-beta)) is greater than
> 1.
> >> How can I remove it.After generating the out put we can omit it, but the
> >> problem is different.
> >>
> >>
>
> --
> Sarah Goslee
> http://www.functionaldiversity.org
>
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