Re: Re: FindRoot question

• To: mathgroup at smc.vnet.net
• Subject: [mg29951] Re: [mg29906] Re: FindRoot question
• From: "Mr. Wizard" <gleam at flashmail.com>
• Date: Thu, 19 Jul 2001 03:57:17 -0400 (EDT)
• References: <9j05h0\$esi\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Chris, unless I don't understand your function, which wouldn't be a first,
I think you're using a needlessly long and complex function.  Try this one

NumberListQ = If[ListQ@#, And @@ NumberQ /@ #, False] &;

Paul

>Just a follow-up on my own question.  Part of the problem was that I
>was calling another homemade function that used FindRoot from within
>FindRoot.  Problems arose when the inner FindRoot got non-numeric
>values for its options.  From other messages I found that using
>_?NumberQ for the inside function should help, but I was passing my
>options as a list, which would not make it by  _?NumberQ.  _?ListQ
>didn't help either, because {x,y} counts as a list as well as {1,2}.
>I ended up writing the following test for a list of numbers, which
>helped.
>
>ListOfNumbersQ[list_]:=Module[{n,ret},
>If[ListQ[list]==False,ret=False,
>n=Length[list];
>ret=True;
>Do[
>If[NumberQ[list[[i]]]==False,ret=False]
>,{i,1,n}];];
>Return[ret]; ];
>
>Thus:
>
>In[21]:=
>ListOfNumbersQ[{1,2}]
>
>Out[21]=
>True
>
>In[23]:=
>ListOfNumbersQ[{x,y}]
>
>Out[23]=
>False
>
>My inside function then begins:
>
>neq[xopts_?ListOfNumbersQ,ni_]:=Module[ ...
>
>-- Chris

```

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