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Student Support Forum: 'Solve[] eqns for real solutions only?' topicStudent Support Forum > General > Archives > "Solve[] eqns for real solutions only?"

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Joseph Norman
01/23/99 1:33pm

Is there a way to find out whether a system of polynomial equations has any real solutions? Solve[] returns complex solutions, which I don't want. For example, I want to be able to discover that (x^2+0.75) + (y^2+0.5) == 1 has no solutions for real x and y. I thought that GroebnerBasis[] would do the trick, but that doesn't always indicate that a system is unsolvable. For example, GroebnerBasis[x^2+1] just returns 1+x^2, which is true but not very useful for determining (automatically) whether the system of one equation x^2+1 == 0 has any real solutions. I'd like to be able to solve systems of several polynomial equations in several variables.

What I'm really trying to do is find out whether there exists a solution to a (generally nonlinear) polynomial inequality with several variables, subject to linear constraints on the variables. But that can be translated into the above problem by substituting different variables.

Thanks, Joe

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Subject (listing for 'Solve[] eqns for real solutions only?')
Author Date Posted
Solve[] eqns for real solutions only? Joseph Norman 01/23/99 1:33pm
Re: Solve[] eqns for real solutions only? John Mac 01/28/99 05:54am
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