Re: Simplifying algebraic expressions

• To: mathgroup at smc.vnet.net
• Subject: [mg66881] Re: [mg66839] Simplifying algebraic expressions
• From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
• Date: Fri, 2 Jun 2006 04:09:19 -0400 (EDT)
• References: <200606011054.GAA20566@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```On 1 Jun 2006, at 19:54, Amitabha Roy wrote:

> Hello:
>
> I would like Mathematica to be able to take an expression, say,
>
> (-1)^{2 x  + 3 y} and be able to simplify to (-1)^y.
>
> Is there a way one can do this ?
>
> Thanks
>

Note that you are using {} instead of (). Different kind of brackets
have completely different meaning in Mathematica.
I have found it amazingly hard to force Mathematica to perform this
simplification. The best I could do is this. We need two rules. rule1
will replace 2x by u and 3y by v. rule 2 does the opposite: it
replaces u by 2x and v by 2y.

rule1 = {2x -> u, 3y -> v};rule2 = Map[Reverse, rule1];

Now:

Simplify[TrigFactor[
FullSimplify[ExpToTrig[
FullSimplify[
ComplexExpand[
(-1)^(2*x + 3*y) /.
rule1], Mod[u, 2] ==
0] /. rule2],
y â?? Integers]],
y â?? Integers]

(-1)^y

Uff... Surely, this ought to be easier...

Andrzej Kozlowski
Tokyo, Japan

```

• Prev by Date: Re: Re: New Analytical Functions - Mathematica Verified
• Next by Date: Re: Pen Lift for FlybackTrace erasure
• Previous by thread: Simplifying algebraic expressions
• Next by thread: Re: Re: Simplifying algebraic expressions