Re: Beginner--How to get a positive solution from Solve Command
- To: mathgroup at smc.vnet.net
- Subject: [mg67795] Re: Beginner--How to get a positive solution from Solve Command
- From: "Valeri Astanoff" <astanoff at yahoo.fr>
- Date: Sat, 8 Jul 2006 04:55:52 -0400 (EDT)
- References: <e8lgq7$ras$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hello Abdou,
You better use FindRoot (with c evaluated)
because Series+Solve does not give you the correct solution.
Example with c=1/2 :
In[1]:=FindRoot[1 -c ArcTanh[\[Xi]]/\[Xi]/.c -> 1/2,{\[Xi],0.5}]
Out[1]={\[Xi] -> 0.957504}
In[2]:=Solve[Normal[Series[1-c
ArcTanh[\[Xi]]/\[Xi],{\[Xi],0,2}]]==0/.c->1/2,\[Xi]]
Out[2]={{\[Xi] -> -Sqrt[3]}, {\[Xi] -> Sqrt[3]}}
V.Astanoff
PS : nous pouvons peut-être correspondre en français