Re: How to get an answer as a Root object?

*To*: mathgroup at smc.vnet.net*Subject*: [mg57145] Re: How to get an answer as a Root object?*From*: "Valeri Astanoff" <astanoff at yahoo.fr>*Date*: Thu, 19 May 2005 03:08:12 -0400 (EDT)*References*: <d6bv8r$pcu$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

The trouble is the derivative being infinite at the solution. I use that trouble to find the solution : In[1]:=f[s_]:= (-1+Sqrt[2]-Sqrt[(1+2*Sqrt[2]-s)*(-1+s)]+s)*(-1-Sqrt[2]+Sqrt[2]*s- Sqrt[-1-2*Sqrt[2]+2*(2+Sqrt[2]-s)*s])-(-1-Sqrt[2]+Sqrt[2]*s+ Sqrt[-1-2*Sqrt[2]+2*(2+Sqrt[2]-s)*s])*(-2-2*Sqrt[2]+2*s+2* Sqrt[1-(1/4)*(-1-Sqrt[2]+Sqrt[(1+2*Sqrt[2]-s)*(-1+s)]+s)^2]) In[2]:=Select[s /. Solve[Numerator[Together[1/f'[s]]] == 0], 2 < # < 3 &] // Simplify Out[2]= 2 + 1/Sqrt[2] In[3]:= % // N Out[3]= 2.70711 That's not what you asked for but that's all I can do! v.a.