Re: FindRoot question

*To*: mathgroup at smc.vnet.net*Subject*: [mg29906] Re: FindRoot question*From*: klaus at biosci.cbs.umn.edu (Chris Klausmeier)*Date*: Wed, 18 Jul 2001 02:08:48 -0400 (EDT)*References*: <9j05h0$esi$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

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