Re: signs in the mathematica output

• To: mathgroup at smc.vnet.net
• Subject: [mg92480] Re: signs in the mathematica output
• From: "David Park" <djmpark at comcast.net>
• Date: Wed, 1 Oct 2008 18:32:01 -0400 (EDT)
• References: <gbulqi\$lcr\$1@smc.vnet.net>

```The handling of signs under simplification is an annoying feature of
Mathematica.

Sometimes the result might look better if you display in TraditionalForm.

Simplify[(1 - s) (1 - a)]
(-1 + a) (-1 + s)
(a - 1) (s - 1)

Otherwise you can Map Minus onto the two factors.

Simplify[(1 - s) (1 - a)]
Minus /@ %
(-1 + a) (-1 + s)
(1 - a) (1 - s)

More generally what you have to do is Map Minus at the location of two
factors. For example if we divide the two factors we could use:

Simplify[(1 - s)/(1 - a)]
MapAt[Minus, %, {{1, 1}, {2}}]
(-1 + s)/(-1 + a)
(1 - s)/(1 - a)

But getting the positions of the two factors and straightening everything up
can be something of a pain in the neck. Maybe someone else will have a
better suggestion.

--
David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/

"Simone Moriconi" <simone.moriconi at eco.unipmn.it> wrote in message
news:gbulqi\$lcr\$1 at smc.vnet.net...
> Hello everybody! I have a problem in using the Mathematica Package which
> is probably a bit stupid but very annoying when you have long
> expressions..
>
> When I "FullSimplify" big equations, in the output the negative sign is
> always put aside i.e. if I do something like:
>
> FullSimplify[(1-s)(1-a)]
>
> I obtain
>
> (-1+s)(-1+a).
>
> Which is very confusing with long and tedius expressions. Does anybody
> know a way to solve this problem?
>
> Thanks a lot for your help!!
>

```

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