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From: "Kittithad Wangveerathananon" <kittithad@startfromyou.com>
Newsgroups: comp.soft-sys.matlab
Subject: suppose I have an equation x^2+x+y^2+3*y=5*y^2+3*y+3*x*y+5 and I want to find the set of (x,y) that satisfy the equation.
Date: Thu, 12 Aug 2010 13:02:06 +0000 (UTC)
Organization: Thammasat University
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Question
How can i do that?
I've been trying, solve, explot and subs.
I can get the graph, but i cannot get the (x,y) pairs that I want.

When I use function solve to solve the equation in term of x or y and then substitute the numeric value for one of them to find the other, I got the problem about complex numer. This might be because that numeric value that I substitute is not the number that satisfy the equation, so the program give me the result in complex number.

Background.
I need to use the pairs to find the optimal value of my objective function.
I tried to use the fmincon, but it gave me the optimal value that is not reliable, so i try to do it manually.
Note that my equality constraint is in the form of the equation in the subject.
I also have a couple of inequality constraints.

Thanks in advance