RE: Canceling square roots with Simplify
- To: mathgroup at smc.vnet.net
- Subject: [mg18321] RE: [mg18211] Canceling square roots with Simplify
- From: "Ersek, Ted R" <ErsekTR at navair.navy.mil>
- Date: Sat, 26 Jun 1999 19:08:01 -0400
- Sender: owner-wri-mathgroup at wolfram.com
Earlier I replied to a message where Everett Farr asked why
Simplify[ Sqrt[b^2]*Sqrt[1/b^2] ]
doesn't simplify to 1.
As already noted by Adam Strzebonski the expression above isn't equal to 1
for all values of (b). One counter example is when (b=I).
For basically the same reason the rule I thought is missing from the
Simplify routine isn't true in general and shouldn't be included.
The rule that isn't true in general is:
----------------
MyRules= {
((zb_^(-1*z1_))^(z2_)):>((zb^z1)^(-z2)),
((zb_^p_?Negative)^z2_):>(zb^(-p))^(-z2) };
----------------
As Adam Strzebonski noted one can use PowerExpand get the expected result.
Also using version 4 one can use Simplify/FullSimplify and indicate certain
variables are part of a specific domain to get the expected result.
Regards,
Ted Ersek