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Re: " for

• To: mathgroup at smc.vnet.net
• Subject: [mg119685] Re: " for
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Fri, 17 Jun 2011 00:10:07 -0400 (EDT)
• Reply-to: hanlonr at cox.net

Assumptions for Simplify or FullSimplify must be simpler.

expr = Conjugate[Sqrt[-(t Cos[2 kx] Cos[ky]) + Cos[kx] + M]];

sub = z -> -(t Cos[2 kx] Cos[ky]) + Cos[kx] + M;

Simplify[expr /. Reverse[sub], z > 0] /. sub

Sqrt[M + Cos[kx] - t*Cos[2*kx]*Cos[ky]]

or 

expr /. Conjugate[Sqrt[pr_]] -> Sqrt[pr]

Sqrt[M + Cos[kx] - t*Cos[2*kx]*Cos[ky]]




Bob Hanlon

---- liblenovo <liblenovo at gmail.com> wrote: 

=============
In[86]:=Simplify[Conjugate[Sqrt[-(t Cos[2 kx] Cos[ky]) + Cos[kx] +
M] ], -(t Cos[2 kx] Cos[ky]) + Cos[kx] + M > 0]

Out[86]= Sqrt[-t cos(2 kx) cos(ky)+cos(kx)+M]^\[Conjugate]

I don't want that  ^\[Conjugate], why it is there?