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