Re: Use of units and simplification
- To: mathgroup at smc.vnet.net
- Subject: [mg38939] Re: Use of units and simplification
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Tue, 21 Jan 2003 07:38:22 -0500 (EST)
- Organization: Universitaet Leipzig
- References: <b08mc9$80e$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
- Sender: owner-wri-mathgroup at wolfram.com
Hi, > Hallo, > > I would like to use the units of Miscellaneous Units (Mathematica 4.2 > Windows). > > 1) Why does Simplify[Sqrt[x*Meter^2]] give > Sqrt[Meter^2*x] ? The result of the simplification is o.k. when I assume > that Meter>=0: > Simplify[Sqrt[x*Meter^2], Meter >= 0] ->Meter*Sqrt[x] > > Of course I could always assume that any unit used is >=0, but that does > not seem to be the right way. A unit can't be >0 or what ever, it mean a real object and not a number. > Am I missing something? Is there a way to get the units "properly" > simplified? You say it already use Simplify[]/FullSimplify[] with a second argument, i.e., Unprotect[Simplify] Simplify[expr_]:=Simplify[expr,Miscellaneous`Units`Meter >=0] Protect[Simplify] > > 2) There is Meter and Centimeter predefined. Where have the Millimeters > gone? I did not succeed in prepending any of the SI unit prefixes. Could > I simply use MilliMeter? Did not really work for me... Convert[1 Milli Meter, Meter] Meter/1000 and Notice the space between Milli and Meter Regards Jens