Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2011

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

Search the Archive

iteration question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg122583] iteration question
  • From: Francisco Gutierrez <fgutiers2002 at yahoo.com>
  • Date: Wed, 2 Nov 2011 06:21:44 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • Reply-to: Francisco Gutierrez <fgutiers2002 at yahoo.com>

Dear Group:

I have a function, and I iterate it using fixedpoint. Something of this sort:

FixedPointList[
 function[arg1,arg2,arg3, #] &, arg4, 
 SameTest -> (Max[Abs[Flatten[#1] - Flatten[#2]]] < 0.01 &)]


I would like to know how many steps it takes this function to converge. I have tried with EvaluationMonitor to no avail:

Block[{veamos, c = 0}, 
  veamos = FixedPoint[
    function[arg1,arg2,arg3, #] &, arg4, 
    SameTest -> (Max[Abs[Flatten[#1] - Flatten[#2]]]< 0.01 &)]; 
  EvaluationMonitor :> c++; {veamos, c}] 


The iterator c simply does not move, and the previous function works ok but returns the value of c as 0.

I tried if this was true with Length[FixedPointList[...]] and the answer was 20 (which should be the value of c in the immediately previous function). In principle, this would solve my problem, but it seems
rather inefficient, especially when the convergence criterion is severe (not 0.01, but say 10^-4).

Is there an efficient and nice way to solve this?

Thanks,

Francisco


  • Prev by Date: Re: Print bug with -script? (quotes display)
  • Next by Date: Re: Export Spoken Sound (Speak-> .wav file?)
  • Previous by thread: Re: Print bug with -script? (quotes display)
  • Next by thread: Re: iteration question