Re: using rules for square roots
- To: mathgroup at smc.vnet.net
- Subject: [mg110284] Re: using rules for square roots
- From: Kent Holing <KHO at statoil.com>
- Date: Fri, 11 Jun 2010 08:44:37 -0400 (EDT)
> Using the Mathematica session > str={Sqrt[a],Sqrt[b^2],Sqrt[c^3],Sqrt[d^4],Sqrt[e^5]}; > g[x_,n_]:=Module[{m=Quotient[n,2]},If[EvenQ[n],x^m,x^m > Sqrt[x]]]; > rule1=Sqrt[x_ y_]->Sqrt[x] Sqrt[y]; > rule2=Sqrt[x_^2]->x; > rule=Sqrt[x_^n_]->x^Quotient[n,2] Sqrt[x^Mod[n,2]]; > rule0=Sqrt[x_^n_]->g[x,n]; > > Now, str/.rule gives the "correct" answer > {Sqrt[a],b,c^3/2,d^2,e^5/2}. > > But why does not rule0 work? > str/.rule returns > {Sqrt[a],b^3/2,c^3/2,d^5/2,e^5/2}. > > I would also like that rule (and rule0) should return > say > e^5/2 as e^2 Sqrt[e]. How can this be accomplished? > > Kent > rule0=Sqrt[x_^n_]->Hold[g[x,n]]; tstr0=ReleaseHold[str/.rule0]; fixes the rule0. I still want to have feedback on my last question, i.e. how to return say expressions like e^5/2 as e^2 Sqrt[e]? Kent