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Re: unwanted Complex result

  • To: mathgroup at smc.vnet.net
  • Subject: [mg91638] Re: unwanted Complex result
  • From: Steven Siew <stevensiew2 at gmail.com>
  • Date: Sat, 30 Aug 2008 01:52:05 -0400 (EDT)
  • References: <g95k8a$543$1@smc.vnet.net>

SelectPositive[soln_] := Select[soln, Apply[And,
   Map[Abs[Part[#, 2]] == Part[#, 2] &, #]] & ]

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

numericsoln = soln/.{windx->1,windy->1,a->1,b->1,c->1,distance-
>20,height->5};

SelectPositive[ N[numericsoln] ]

{{speed->1.11901}}



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