Re: Re: Simplification and Arg[]

*To*: mathgroup at smc.vnet.net*Subject*: [mg66612] Re: [mg66603] Re: [mg66593] Simplification and Arg[]*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Wed, 24 May 2006 03:01:47 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On 23 May 2006, at 07:14, David Park wrote: > Andrew, > > For doing complex algebra the BIG, BIG command is ComplexExpand. > One can > hardly get along without it. But for some reason, users starting > out with > complex algebra on Mathematica frequently overlook it. (Maybe they > should > have called it ComplexSimplify?) I don't think so: it quite properly called ComplexExpand because it "expands". In fact, for purely real expressions it will usually return the same output as Expand: ComplexExpand[(a + b)*(c + d)] a*c + b*c + a*d + b*d On the other hand if a and b are complex, the expression returned by ComplexExpand will certainly in general not be simpler than the original one: ComplexExpand[(a + b)*(c + d), {a, b, c, d}] (-Im[a])*Im[c] - Im[b]*Im[c] - Im[a]*Im[d] - Im[b]*Im[d] + Re[a]*Re [c] + Re[b]*Re[c] + Re[a]*Re[d] + Re[b]*Re[d] + I*(Im[c]*Re[a] + Im[d]*Re[a] + Im[c]*Re[b] + Im[d]*Re[b] + Im[a]*Re [c] + Im[b]*Re[c] + Im[a]*Re[d] + Im[b]*Re[d]) I do not think I would call this "simplifying", would you? ;-) Andrzej Kozlowski Tokyo, Japan