Re: anything faster than Solve[] for solving sets of polynomial equations symbolically?
- To: mathgroup at smc.vnet.net
- Subject: [mg118599] Re: anything faster than Solve[] for solving sets of polynomial equations symbolically?
- From: David Skulsky <edskulsky at gmail.com>
- Date: Wed, 4 May 2011 06:33:07 -0400 (EDT)
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