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

MathGroup Archive 2011

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

Search the Archive

A basic question about RecurrenceTable - warning messages

  • To: mathgroup at smc.vnet.net
  • Subject: [mg122235] A basic question about RecurrenceTable - warning messages
  • From: victorphy <vbapst at gmail.com>
  • Date: Fri, 21 Oct 2011 07:28:36 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Hello,


I have a small and basic question about RecurrenceTable.

I would like to solve f(x,a)==0 where x is the unknown and a is a
parameter. As f has several zeros I want to follow one zero when
varying a.

Thus I write something like that :

f[x_,a_] :=  -(x - a)^3 + (x - a)

soltest[a_, b_] :=  x /. FindRoot[f[x, a], {x, b}]

RecurrenceTable[{a[n + 1] == soltest[n/10, a[n]], a[0] == -1}, a, {n,
10}]


I get the correct output but a lot of warning messages :

FindRoot::srect: "Value a[n] in search specification {x,a[n]} is not a
number or array of numbers
ReplaceAll::reps: "{FindRoot[f[x,n/10],{x,a[n]}]} is neither a list of
replacement rules nor a valid dispatch table, and so cannot be used
for replacing



Is there something that I am doing wrong ? Or is it just normal ?

Thank you very much for your answers.

Victor



  • Prev by Date: Re: Ticks without labels
  • Next by Date: Re: Problem with "Which"
  • Previous by thread: A couple of questions
  • Next by thread: Re: A basic question about RecurrenceTable - warning messages