Re: how to solve this problem?

*To*: mathgroup at smc.vnet.net*Subject*: [mg95107] Re: [mg95059] how to solve this problem?*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Tue, 6 Jan 2009 04:13:54 -0500 (EST)*Reply-to*: hanlonr at cox.net

Clear[x, y]; z = x + I*y; Assuming[{Element[{x, y}, Reals]}, Simplify[Re[z]]] x Assuming[{Element[{x, y}, Reals]}, Simplify[Im[z]]] y Or something like Clear[defineReal]; SetAttributes[defineReal, Listable]; defineReal[x_Symbol] := Module[{}, x /: Re[x] = x; x /: Im[x] = 0;] defineReal[{x, y}]; Re[z] x Im[z] y Bob Hanlon On Mon, Jan 5, 2009 at 7:05 AM , Ising wrote: > Hi: > I want to define the variables x and y are real at first,then: > z=x+I*y; > Re[z]=x > Im[z]=y > Using "Assumptions" "Assuming"? But i don not know how to use it. Is > there other ways to get that? > I know in another system, it is easy, as in > assume(x,real,y,real); So what is in Mathematica? > Thanks!