Re: [R] dynamics of functions

[Barry Rowlingson]

Hotz, T. 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)
 Or the following:

iterFun <-
  function(f,n,x,...){
    if(n==0){return(x)}
    for(i in 1:n){
      x<-f(x,...)
    }
    return(x)
  }
 If you want to construct an arbitrary function without naming it, you 
can do something like this:

> iterFun(function(z){3.9*z*(1-z)},121,.6)
[1] 0.6449397
 And the ... part means you can try different constants in your function:

> iterFun(function(z,a){a*z*(1-z)},121,.6,a=3.9)
[1] 0.6449397
> iterFun(function(z,a){a*z*(1-z)},121,.6,a=3.901)
[1] 0.09416016
> iterFun(function(z,a){a*z*(1-z)},121,.6,a=3.900001)
[1] 0.7612195
 Fun with functions.

Baz

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