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MathGroup Archive 2004

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FindRoot complains under version 5.0

  • To: mathgroup at smc.vnet.net
  • Subject: [mg46125] FindRoot complains under version 5.0
  • From: Sebastian Kubis <seb at z4seb.ifj.edu.pl>
  • Date: Sat, 7 Feb 2004 04:02:07 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

in version 4.1 I was used to nest FindRoot in another FindRoot
in the follwing way:


arcsin[y_]:=x/.FindRoot[Sin[x]==y,{x,.3,.4}]

sin[\[Alpha]_]:=z/.FindRoot[arcsin[z]==\[Alpha] ,{z,0,.5}]

and there was no problem with this, but now Mathematica 5.0 reports
an error, although finally gets the correct result:

In[3]:= sin[30. Degree]

FindRoot::"nlnum" : 
   The function value {0.29552020 - 1. z} is not a list of numbers
   with dimensions {1} at {x} = {0.3}. More...

ReplaceAll::reps: {FindRoot[Sin[x] == z, {x, 0.3, 0.4}]}
  is neither a list of replacement rules nor a valid dispatch table, and so
  cannot be used for replacing. More...

Out[3]:=0.5 

What has changed in ver.5.0 ?

Thanks,

Seb


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