dynamics of functions
On Thu, 5 Jun 2003, Tobias Verbeke wrote:
...
What about the following function?
iterate<-function(f,n,x){
if(n==0) return(x)
y<-x
for(i in 1:n)y<-f(y)
y
}
iterate(sqrt,3,256)
Thank you very much, this certainly helps. I'm still curious, though, to know how to write the expression of my function immediately as the argument f. I can define it outside of the function
aap <- function(x) -x^3
and use it as argument
iterate(aap,3,256),
but I seem not to be clever enough to write a function that receives the following as input
iterate(-x^3,3,256)
That's an expression, not a function, and you would need some convention that it is x that should be varied. You can do that: see curve() for example. Or just use iterate(function(x) -x^3, 3, 256) Someone seems very adverse to using the spacebar!
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595