ans
}
### ... and their primitives:
-BIRTH.logis <- function(a, b) log(exp(-a*t) + exp(b))/a + t
+BIRTH.logis <- function(t) log(exp(-a*t) + exp(b))/a + t
BIRTH.step <- function(t)
{
if (t <= Tcl) return(t*l1)
### fit both models:
yule.time(bird.families, birth.logis)
yule.time(bird.families, birth.logis, BIRTH.logis) # same but faster
-yule.time(bird.families, birth.step) # fails
+\dontrun{yule.time(bird.families, birth.step)} # fails
yule.time(bird.families, birth.step, BIRTH.step)
}
\keyword{models}