Re: "Alternating" function

*To*: mathgroup at smc.vnet.net*Subject*: [mg63271] Re: [mg63260] "Alternating" function*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Thu, 22 Dec 2005 00:04:33 -0500 (EST)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

expr=x+f[x-f[x+f[x-f[x+f[x]]]]]; expr==Module[{n=1}, Nest[x-(-1)^n++*f[#]&, x, 5]] True expr==Module[{n=1}, Nest[x-Cos[Pi*n++]*f[#]&, x, 5]] True Bob Hanlon > > From: Renan <renan.birck at gmail.com> To: mathgroup at smc.vnet.net > Date: 2005/12/20 Tue PM 11:35:44 EST > Subject: [mg63271] [mg63260] "Alternating" function > > 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. > > > > > -- > Thanks/obrigado, Renan "Wishmaster" Birck - Canoas, Rio Grande do Sul, Brasil > MSN: wizard_of_yendor at hotmail.com > Orkut: http://www.orkut.com/Profile.aspx?uid=2202360379963855296 > >