Re: Problems with simplify and Sqrt[a^2]

*To*: mathgroup at smc.vnet.net*Subject*: [mg73941] Re: Problems with simplify and Sqrt[a^2]*From*: Bhuvanesh <lalu_bhatt at yahoo.com>*Date*: Sat, 3 Mar 2007 01:13:31 -0500 (EST)

Sqrt[a^2] is equal to a only for Re[a]>0; for Re[a]<0 it is -a. So Mathematica is being careful and not making assumptions that could end up giving a wrong result. You can get what you want by using PowerExpand. In[1]:= PowerExpand[v3/Sqrt[v1^2]/Sqrt[v2^2] - v3/v1/v2] Out[1]= 0 Another way is to use Simplify (or FullSimplify) with assumptions: Simplify[expression, v1>0 && v2>0 && ...] Bhuvanesh, Wolfram Research.