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Re: anything faster than Solve[] for solving sets of polynomial equations symbolically?

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  Re: anything faster than Solve[] for solving sets of polynomial equations symbolically? David Skulsky <edskulsky@gmail.com> - 2011-05-04 10:33 +0000

#2079 — Re: anything faster than Solve[] for solving sets of polynomial equations symbolically?

I'm not sure why you're not getting a solution (not enough memory, perhaps?, but my machine provides an answer within a few seconds.  However, the solution is a big mess.  To make it a bit more tractable (though still far too large to post here), you could do the following:


eqs = {-k5 x1 x3 + k6 x4 == 0,
   k1 x1 - k4 x2 - 2 k2 x2^2 + 2 k3 x3 + k7 x4 == 0,
   k2 x2^2 - k3 x3 - k5 x1 x3 + k6 x4 == 0, x1 + x4 - Xtot == 0};

sol = Solve[eqs, {x1, x2, x3, x4}, Reals];

solSimple =
 Assuming[{k1 >= 0, k2 >= 0, k3 >= 0, k4 >= 0, k5 >= 0, k6 >= 0,
   k7 >= 0, Xtot >= 0}, Simplify[sol]]

Taking Dimensions[solSimple] yields {3,4} which suggests (I think) that there are 3 solutions to the problem.

David

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