       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 == -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

```

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