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MathGroup Archive 1999

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Re: Forcing Re[]'s to be Real

  • To: mathgroup at
  • Subject: [mg18268] Re: [mg18223] Forcing Re[]'s to be Real
  • From: Haiduke Sarafian <has2 at>
  • Date: Thu, 24 Jun 1999 14:24:53 -0400
  • References: <>
  • Sender: owner-wri-mathgroup at

At 03:15 PM 6/23/99 -0700, Anthony Foglia wrote:
>On Wed, 23 Jun 1999, Haiduke Sarafian wrote:
>> Anthony;  the source of the problem is the argument of  k[w] function - It
>> should read k[w_]:=...
>	Actually I have that correct in my code, but mistyped when I wrote
>the message.
>> As you suggested,  to extract the Re and Im components of k[w] apply
>> Re[ComplexExpand[k[w]] and Im[ComplexExpand[k[w]] - then you can graph the
>> outputs. Cheers
>	Nope, still can't.  Still getting "...not a machine-sized real"
Anthony;  I am surprised with our "Nope" answer!!   If you define the k[w]
correctly then you can generate two numerical tables one for
Re[ComplexExpand[k[w]]] and the other one for Im[...] for a range of w
before graph them -  this will ensure the graph process.

tr1:=N[Table[r1,{w,0,10}]  (* this will produce a set of real values *)
Plor1=Plot[r1,{w,0,10}];  (* this will plot the r1 function which behaves
linearly *)
You can try the same procedure for the Im part of the k[w].  I graphed the
Re and Im pieces of the k[w] and naturally they worked!!

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