Re: Adding equations

*To*: mathgroup at smc.vnet.net*Subject*: [mg14403] Re: Adding equations*From*: Paul Abbott <paul at physics.uwa.edu.au>*Date*: Sun, 18 Oct 1998 15:10:08 -0400*Organization*: University of Western Australia*References*: <703u1n$hup@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Lawrence Walker wrote: > Is there a way to elegantly add (sub, mult, div) two equations? Also is > there an elegant way to add (sub, mult, div) an expression to both > sides of an equation? If you modify Equal as follows (as suggested by Roman Maeder) then any Listable operations are automatically applied to both sides of any equality: Unprotect[Equal]; listableQ[f_] := MemberQ[Attributes[f], Listable] Equal/: lhs:(f_Symbol)?listableQ[___, _Equal, ___] := Thread[Unevaluated[lhs], Equal] Protect[Equal]; Cheers, Paul ____________________________________________________________________ Paul Abbott Phone: +61-8-9380-2734 Department of Physics Fax: +61-8-9380-1014 The University of Western Australia Nedlands WA 6907 mailto:paul at physics.uwa.edu.au AUSTRALIA http://www.physics.uwa.edu.au/~paul God IS a weakly left-handed dice player ____________________________________________________________________