MathGroup Archive 2005

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: "Alternating" function


On Dec 20, 2005, at 11:35 PM, Renan wrote:

> Hello,
>
> I want to make a "nested function" like: x + f[x - f[x + f[x - f[x  
> + f[x]]]]].
>
> I've tried using Nest but I don't find how to keep switching between
> Plus and Minus: I would need something that would return an "index" so
> I could keep track of when I need to "switch" the operation. (e.g. if
> the "index" is odd, the operation is "Plus", otherwise is "Minus")
>
> How can I make this? I looked in the help but didn't find any  
> informations.
>
> Thanks.

One way is to use Fold instead of Nest

Fold[x+#2 f[#1]&,x,Table[(-1)^i,{i,0,n-1}]

where n in is the desired level of nesting.

Regards,

Ssezi


  • Prev by Date: Re: "Alternating" function
  • Next by Date: Re: Convincing Mathematica that Sqrt[a+b]Sqrt[a-b]==Sqrt[a^2+b^2]
  • Previous by thread: Re: "Alternating" function
  • Next by thread: Re: "Alternating" function