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RE: unwanted Complex result

• To: mathgroup at smc.vnet.net
• Subject: [mg91594] RE: [mg91589] unwanted Complex result
• From: "Jaccard Florian" <Florian.Jaccard at he-arc.ch>
• Date: Thu, 28 Aug 2008 07:39:05 -0400 (EDT)
• References: <200808280718.DAA04808@smc.vnet.net>

Hello,

I use :

Reduce[equations,vars,Reals]

I think, it's the best way...

And if you want rules, write :

ToRules[Reduce[equations,vars,Reals]]

You could also select your real solutions using "Cases", but it's more =
complicated.

Regards

F.Jaccard

-----Message d'origine-----
De : John Rivers [mailto:first10 at btinternet.com]
Envoy=E9 : jeudi, 28. ao=FBt 2008 09:19
=C0 : mathgroup at smc.vnet.net
Objet : [mg91589] unwanted Complex result

Solve[
(Sqrt[speed ^ 2 - windx ^ 2] + windy) / a speed ^ 2 + b speed + c ==
distance / height
, speed]

this works but returns 4 solutions that all return complex numbers

I need a real number

how do I:

- convert a complex result into real number
or
- solve the equation to give only real numbers

• References:
  • unwanted Complex result
    • From: John Rivers <first10@btinternet.com>