Re: Replace not spotting a replacement
- To: mathgroup at smc.vnet.net
- Subject: [mg103583] Re: [mg103399] Replace not spotting a replacement
- From: "David Carter-Hitchin" <david at carter-hitchin.clara.co.uk>
- Date: Tue, 29 Sep 2009 07:37:53 -0400 (EDT)
- References: <22608339.1253442945257.JavaMail.root@n11> <003001ca39e9$96f2d3e0$c4d87ba0$@net>
Thanks, David, Same solution, but simpler than Bob's. Regards, David. > -----Original Message----- > From: David Park [mailto:djmpark at comcast.net] > Sent: 20 September 2009 12:58 > To: 'claranet news'; mathgroup at smc.vnet.net > Subject: RE: [mg103399] Replace not spotting a replacement > > Replace does not Solve or do algebra. Replace only matches a pattern > and > that pattern does not occur in your expression. > > Solve for Tau in terms of Mu and then replace. > > Sqrt[2 \[Pi] \[Tau]] == \[Mu] > \[Tau]sol = Part[Solve[%, \[Tau]], 1, 1] > Sqrt[2 \[Pi]] \[Tau]^(3/2) /. \[Tau]sol > > > David Park > djmpark at comcast.net > http://home.comcast.net/~djmpark/ > > > From: claranet news [mailto:david at carter-hitchin.clara.co.uk] > > > 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. > > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.409 / Virus Database: 270.13.94/2366 - Release Date: > 09/19/09 17:50:00