Re: Forcing Re[]'s to be Real
- To: mathgroup at smc.vnet.net
- Subject: [mg18256] Re: Forcing Re[]'s to be Real
- From: "Neal E. Tornberg" <neal.e.tornberg at boeing.com>
- Date: Thu, 24 Jun 1999 14:24:39 -0400
- Organization: Boeing
- References: <7kpbj1$4b8@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
try Re[Sqrt[1.+I]] i.e. use a real constant to force Mathematica to do the numerics Try defining k[w_Real]:=.... Anthony Foglia wrote: > > I seem to have found an interesting problem involving computing the > real part of complex numbers. (Interesting, in that it wasn't there a few > weeks ago when I ran the (as-far-as-i-can-remember) exact same code.) > > I have a complex function: > > k[w] := Sqrt[w^2 (1 + (2 / (1 + I w)))] > > I want to graph the real and imaginary parts, but Mathematica doesn't want > to express the Re[k[w]] as a real number. What do I mean? Well, if I > type: > > Re[Sqrt[1+I]] > > I get out > > Re[Sqrt[1+I]] > > Same if I do Re[ComplexExpand[Sqrt[1+I]]], or Re[(1+I)^(1/2)]. But if I > enter: > > Re[ComplexExpand[(1+I)^(1/2)] > > Mathematica is kind enough to respond with: > > 2^(1/4) Cos[Pi/8] > > I'm certain that this is the root of my problem, but I'll be damned if I > know why Mathematica doesn't like it now, but did a few weeks ago. Any > help? > > --Anthony -- Neal E. Tornberg neal.e.tornberg at boeing.com Nobody here thinks I speak for Boeing. You shouldn't either.