       Re: Simplifying things

• To: mathgroup at smc.vnet.net
• Subject: [mg26095] Re: [mg26070] Simplifying things
• From: Tomas Garza <tgarza01 at prodigy.net.mx>
• Date: Tue, 28 Nov 2000 01:55:39 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```Unfortunately, V.3 has not yet incorporated a nice feature of Simplify,
viz. Assumptions. In Version 4 your problem would be easily taken care
of by means of

In:=
Simplify[Sqrt[a^2], a > 0]
Out=
a

In Version 3 you get

In:=
Simplify[Sqrt[a^2]]
Out:
Sqrt[a^2]

because Mathematica doesn't know whether a>0. One possible way out - if
you know that a>0 - would be to replace a by Abs[a] and then back again:

In:=
(Sqrt[a^2] /. a -> Abs[a]) /. Abs[a] -> a
Out=
a

Tomas Garza
Mexico City
<djago at my-deja.com> wrote:

> I need to simplify looooong equations, but don't know how to get rid
of
> those terms like:
>
> Sqrt[a^2]
>
> when a is a real positive variable... How can I tell Mathematica 3 to
> simplify this?

```

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