Re: Replace not spotting a replacement
- To: mathgroup at smc.vnet.net
- Subject: [mg103433] Re: [mg103399] Replace not spotting a replacement
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Mon, 21 Sep 2009 05:52:57 -0400 (EDT)
- Reply-to: hanlonr at cox.net
Make the LHS of a rule as simple as possible
sub = Solve[Equal @@ (Sqrt[2*Pi*\[Tau]] -> \[Mu]), \[Tau]][[1]]
{\[Tau] -> \[Mu]^2/(2*Pi)}
Simplify[Sqrt[2*Pi]*\[Tau]^(3/2) /. sub,
Element[\[Mu], Reals]]
Abs[\[Mu]]^3/(2*Pi)
Simplify[Sqrt[2*Pi]*\[Tau]^(3/2) /. sub,
\[Mu] >= 0]
\[Mu]^3/(2*Pi)
Bob Hanlon
---- claranet news <david at carter-hitchin.clara.co.uk> wrote:
=============
Hi Folks,
Seems the replace function is being a bit dim here. This fails:
Sqrt[2 \[Pi]] \[Tau]^(3/2) /. Sqrt[ 2 \[Pi] \[Tau]] -> \[Mu]
Apologies if this is an FAQ - I couldn't see anything about it. What do I
need to do here to coerce Mathematica into making this replacement? I tried using the
Collect function on tau first, but that didn't seem to work. I also tried
re-writing the replacement rule as
Sqrt[2 \[Pi]] \[Tau]^(3/2) /. Sqrt[ 2 \[Pi] ] t^(1/2) -> \[Mu]
But still no joy.
Anyone know?
Many thanks,
David.