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AW: Solve real roots only ?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg43601] AW: [mg43585] Solve real roots only ?
  • From: Matthias.Bode at oppenheim.de
  • Date: Tue, 23 Sep 2003 04:01:47 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Hello Pavel,

the following does work (V. 4.1.1):

 Needs["Miscellaneous`RealOnly`"]; 

f = a - (1 - x)*Sqrt[20*x - 20000*y];
g = (a*(1 - y) -1000*y*(1 - x))/(10 - x);
Solve[{f == 0,g == 0}, {x, y}]

The output is quite lengthy.

Best regards,

Matthias Bode
Sal. Oppenheim jr. & Cie. KGaA
Koenigsberger Strasse 29
D-60487 Frankfurt am Main
GERMANY
Tel.: +49(0)69 71 34 53 80
Mobile: +49(0)172 6 74 95 77
Fax: +49(0)69 71 34 95 380
E-mail: matthias.bode at oppenheim.de
Internet: http://www.oppenheim.de




-----Ursprungliche Nachricht-----
Von: Pavel Pokorny [mailto:Pavel.Pokorny at vscht.cz]
Gesendet: Montag, 22. September 2003 09:14
An: mathgroup at smc.vnet.net
Betreff: [mg43585] Solve real roots only ?



  Dear Mathematica friends,

how can I tell Solve to find real roots only?
I tried RealOnly but it makes this little program to crash!

   Needs["Miscellaneous`RealOnly`"]; 
   f = a - (1-x) Sqrt[20 x - 20000 y];
   g = (a(1-y)- 1000 y (1-x))/(10-x);
   s = Solve [ f==0 && g==0, {x,y}];
   xs = x /. s;
   xx = Series [xs, {a,0,2}];

Is it my fault?

Thanks

-- 
Pavel Pokorny
Math Dept, Prague Institute of Chemical Technology
http://www.vscht.cz/mat/Pavel.Pokorny


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