Re: anything faster than Solve[] for solving sets of polynomial equations symbolically?
- To: mathgroup at smc.vnet.net
- Subject: [mg118702] Re: anything faster than Solve[] for solving sets of polynomial equations symbolically?
- From: Dan Siegal-Gaskins <dsg at dantimatter.com>
- Date: Sat, 7 May 2011 07:35:42 -0400 (EDT)
> The code runs here, exactly as you see it below.
>
> 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};
> nonNeg = Thread[{k1, k2, k3, k4, k5, k6, k7, Xtot} >= 0];
> real = Element[vars = {x1, x2, x3, x4}, Reals];
> problem = Flatten@{eqs, nonNeg};
> Solve[problem, Reals] // FullSimplify
>
> $Version
>
> "8.0 for Mac OS X x86 (64-bit) (February 23, 2011)"
>
> Bobby
hmmm... it looks like I'm experiencing a version-related problem then:
In[1]:= 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};
nonNeg=Thread[{k1,k2,k3,k4,k5,k6,k7,Xtot}>=0];
real=Element[vars={x1,x2,x3,x4},Reals];
problem=Flatten@{eqs,nonNeg};
[problem,Reals]//FullSimplify
During evaluation of In[1]:=
Solve::eqf: Xtot>=0 is not a well-formed equation. >>
Out[5]= Solve[{k5 x1 x3==k6 x4,k1 x1+2 k3 x3+k7 x4==x2 (k4+2 k2 x2),k2 x2^2+k6 x4==(k3+k5 x1) x3, x1+x4==Xtot, k1>=0, k2>=0,k3>=0,k4>=0, k5>=0,k6>=0,k7>=0,Xtot>=0},Reals]
In[6]:= $Version
Out[6]= 7.0 for Mac OS X x86 (64-bit) (February 19, 2009)
I'll see if i can get my hands on version 8
thanks
dan