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Re: transforming exponential of sums into product of exponentials

• To: mathgroup at smc.vnet.net
• Subject: [mg48668] Re: [mg48654] transforming exponential of sums into product of exponentials
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Thu, 10 Jun 2004 02:43:01 -0400 (EDT)
• Reply-to: hanlonr at cox.net
• Sender: owner-wri-mathgroup at wolfram.com

It doesn't refuse to do the transformation, it just immediately undoes the 
transformation.  Just write the product and you will see that it simplifies the 
expression.

Exp[a]Exp[b]

E^(a + b)

You could use Hold

Exp[x+y]/.Exp[a_+b_]\[Rule]Hold[Exp[a]Exp[b]]

Hold[E^x*E^y]

%//ReleaseHold

E^(x + y)


Bob Hanlon
> 
> From: "Karim Mehadhebi" <Karim.Mehadhebi at wanadoo.fr>
To: mathgroup at smc.vnet.net
> Date: 2004/06/09 Wed AM 04:17:34 EDT
> To: mathgroup at smc.vnet.net
> Subject: [mg48668] [mg48654] transforming exponential of sums into product of 
exponentials
> 
> Dear All,
> 
> I can not understand why Mathmatica refuses to apply rules which 
transform
> exponenials of sums into product of exponentails.
> 
> For instance,
> f[x+y] /. f[a_ + b_]-> f[a] f[b] returns f[x] f[y],
> whereas
> Exp[x+y] /. Exp[a_+b_]->Exp[a]Exp[b] still returns Exp[x+y]
> 
> Any help greatly appreciated
> 
> 
> 
> 
> 
> 

Bob Hanlon
Chantilly, VA