Dear R users,
i would like to transform the following function from R-code to C-code and call
it from R in order to speed up the computation because in my other functions
this function is called many times.
`dgcpois` <- function(z, lambda1, lambda2)
{
`f1` <- function(alpha, lambda1, lambda2)
return(exp(log(lambda1) * (alpha - 1) - lambda2 * lgamma(alpha)))
`f2` <- function(lambda1, lambda2)
return(integrate(f1, lower=1, upper=Inf, lambda1=lambda1,
lambda2=lambda2)$value)
return(exp(log(lambda1) * z - lambda2 * lgamma(z + 1) -
log(f2(lambda1=lambda1, lambda2=lambda2))))
}
In order to do this i read for example dgamma.c or dpois.c but for my it seems
rather cryptic and so i would like get some advice in writing the c-function.
First of all i think i cannot call the integrate r-function from c so i have to
use the internal c-function of integrate here?
Thanks,
Andreas
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