Displaying 2 results from an estimated 2 matches for "calsta".
2011 Feb 12
1
how to improve the precison of this calculation?
..."result", this is just a picture of the calculation which can't implement due to the precision problem
i<-0:(c-1)
vec<-choose(n,i)*choose(NT-n,CT-i) #get the vector which need summation
result<-log(sum(vec)) #get the log of summation
# thanks to Petr, we have a solution
calsta <- function(c, n) {
i <- seq(from=0, length=c)
logx <- lchoose(NT-n, CT-i) + lchoose(n, i)
logmax <- max(logx)
logmax + log(sum(exp(logx - logmax)))
}
# now, new problem arise, in theory, the "result" of different (c,n) pair should most probably differ, so I can order t...
2011 Feb 11
3
How can we make a vector call a function element-wise efficiently?
Hello
I have a time-comsuming program which need to simplify, I have tested the annotated program as follow:
> #define function which will be call
> calsta <- function(c, n=100000)
+ {
+ i <- seq(from=0, length=c)
+ logx <- lchoose(NT-n, CT-i) + lchoose(n, i)
+ logmax <- max(logx)
+ logmax + log(sum(exp(logx - logmax)))
+ }
> CT=6000 #assignment to CT
> NT=29535210 #assignment to NT
>
> vec<-c(2331,524,918,21...