Re: Finding length in recursive definition?
- To: mathgroup at smc.vnet.net
- Subject: [mg60905] Re: Finding length in recursive definition?
- From: Peter Pein <petsie at dordos.net>
- Date: Mon, 3 Oct 2005 04:06:04 -0400 (EDT)
- References: <firstname.lastname@example.org> <email@example.com>
- Sender: owner-wri-mathgroup at wolfram.com
Scout schrieb: > Hi Jose, > If I've well understood your question > about how many values of a recursive function f are stored in memory, > you can try this: > > Length[DownValues[f]] - 1 > > where -1 counts the definition of f itself. > > ~Scout~ > > "Jose Reckoner" > >>I have something like: >>f = 1 >>f = 3 >>f[n_] := f[n] = f[n - 1] + f[n - 2] >> >>and in the course of work, f[n] gets evaluated an unknown number of >>times resulting in >> >> >>>>?f >> >>f = 1 >>f = 3 >>f = 4 >>f[n_] := f[n] = f[n - 1] + f[n - 2] >> >>I want to figure out the greatest integer n such that f[n] has already >>been computed and is stored. In this case, it is 3. >> >>How can I do this? >> >>Thanks! >> >>Jose >> > > Hi ~Scout~, what would you do for this function: In:= Clear[f]; f=1; f=1; f[n_Integer?EvenQ]:=f[n]=1+f[n/2]; f[n_]:=f[n]=f[n-1]-1; In:= f Out= 3 In:= Definition[f]//InputForm Out//InputForm= f = 1 f = 1 f = 2 f = 3 f = 4 f = 3 f[(n_Integer)?EvenQ] := f[n] = 1 + f[n/2] f[n_] := f[n] = f[n - 1] - 1 ? Peter