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Re: Sinh, Cosh and all that

• To: mathgroup at smc.vnet.net
• Subject: [mg2238] Re: Sinh, Cosh and all that
• From: "Brian J. Albright" <albright at physics.ucla.edu>
• Date: Wed, 18 Oct 1995 01:53:56 -0400
• Organization: UCLA Department of Physics and Astronomy

Kenny Breuer <breuer at mit.edu> wrote:
>I'm looking for a set of transformation rules that will convert
>expoentials to hyperbolic functions (analagous to the function
>ComplexToTrig in the Trigonometry package)
>
>For example:
>In:	ConvertToHyp[ Exp[3x] + Exp[-3x] ]
>
>Out:   2 Cosh[3x]
>
>Thanks
>
>Kenny Breuer
>breuer@mit
>

Hi.

Perhaps you might try

  In[1]:= ExpToHyp[x_] := x //. Exp[a_] -> (Cosh[a] + Sinh[a])

e.g. 

  In[2]:= ExpToHyp[ Exp[s] - Exp[-s] + Exp[3 x] + Exp[-3 x] ]

  Out[2]:= 2 Cosh[3 x] + 2 Sinh[s]


-Brian


-- 
Brian J. Albright                            |
Department of Physics and Astronomy, UCLA    |      To err is human...
albright at physics.ucla.edu                    |         to err really big
http://bohm.physics.ucla.edu/~albright       |             is government.