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Re: Help needed

  • To: mathgroup at smc.vnet.net
  • Subject: [mg132037] Re: Help needed
  • From: "Dr. Wolfgang Hintze" <weh at snafu.de>
  • Date: Thu, 21 Nov 2013 23:01:50 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
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  • References: <l6i3h3$80f$1@smc.vnet.net>

Am Mittwoch, 20. November 2013 11:39:31 UTC+1 schrieb Artur:
> Dear Mathematica Gurus!
> 
> Who have good computer with big RAM memory and will be able to help me 
> 
> solve following 13 eq with 13 variables (my computer have 8MB and it is 
> 
> not sufficient). If You will be reached some result write to me 
> 
> privately because from unknown reason I don't receiving posts now from 
> 
> mathgroup):
> 
> 
> 
> Solve[{e^3 == e1 e2^2, -1 == 2 c2 e1 e2 + c1 e2^2,
> 
>    3 b e^2 == c2^2 e1 + 2 c1 c2 e2 + 2 b2 e1 e2 + b1 e2^2,
> 
>    0 == c1 c2^2 + 2 b2 c2 e1 + 2 b2 c1 e2 + 2 b1 c2 e2 + 2 a2 e1 e2 +
> 
>      a1 e2^2,
> 
>    3 b^2 e + 3 e^2 f ==
> 
>     2 b2 c1 c2 + b1 c2^2 + b2^2 e1 + 2 a2 c2 e1 + 2 b1 b2 e2 +
> 
>      2 a2 c1 e2 + 2 a1 c2 e2 + e2^2 f1 + 2 e1 e2 f2,
> 
>    0 == b2^2 c1 + 2 b1 b2 c2 + 2 a2 c1 c2 + a1 c2^2 + 2 a2 b2 e1 +
> 
>      2 a2 b1 e2 + 2 a1 b2 e2 + 2 c2 e2 f1 + 2 c2 e1 f2 + 2 c1 e2 f2,
> 
>    b^3 + 6 b e f ==
> 
>     b1 b2^2 + 2 a2 b2 c1 + 2 a2 b1 c2 + 2 a1 b2 c2 + a2^2 e1 +
> 
>      2 a1 a2 e2 + c2^2 f1 + 2 b2 e2 f1 + 2 c1 c2 f2 + 2 b2 e1 f2 +
> 
>      2 b1 e2 f2,
> 
>    0 == 2 a2 b1 b2 + a1 b2^2 + a2^2 c1 + 2 a1 a2 c2 + 2 b2 c2 f1 +
> 
>      2 a2 e2 f1 + 2 b2 c1 f2 + 2 b1 c2 f2 + 2 a2 e1 f2 + 2 a1 e2 f2,
> 
>    3 b^2 f + 3 e f^2 ==
> 
>     a2^2 b1 + 2 a1 a2 b2 + b2^2 f1 + 2 a2 c2 f1 + 2 b1 b2 f2 +
> 
>      2 a2 c1 f2 + 2 a1 c2 f2 + 2 e2 f1 f2 + e1 f2^2,
> 
>    0 == a1 a2^2 + 2 a2 b2 f1 + 2 a2 b1 f2 + 2 a1 b2 f2 + 2 c2 f1 f2 +
> 
>      c1 f2^2, 3 b f^2 == a2^2 f1 + 2 a1 a2 f2 + 2 b2 f1 f2 + b1 f2^2,
> 
>    0 == 2 a2 f1 f2 + a1 f2^2, f^3 == f1 f2^2}, {f, f1, f2, e, e1, e2,
> 
>    a1, a2, b, b1, b2, c1, c2}]
> 
> 
> 
> (* best wishes Artur *)

Arthur,

I suggest that you try to find a numeric solution. Otherwiese Mathematica is building up a huge tower of symbolic stuff quickly filling the available memory.

Try this

eq = [{e^3 == e1 e2^2, -1 == 2 c2 e1 e2 + c1 e2^2, 
   3 b e^2 == c2^2 e1 + 2 c1 c2 e2 + 2 b2 e1 e2 + b1 e2^2, 
   0 == c1 c2^2 + 2 b2 c2 e1 + 2 b2 c1 e2 + 2 b1 c2 e2 + 2 a2 e1 e2 + 
     a1 e2^2,
   3 b^2 e + 3 e^2 f == 
    2 b2 c1 c2 + b1 c2^2 + b2^2 e1 + 2 a2 c2 e1 + 2 b1 b2 e2 + 
     2 a2 c1 e2 + 2 a1 c2 e2 + e2^2 f1 + 2 e1 e2 f2, 
   0 == b2^2 c1 + 2 b1 b2 c2 + 2 a2 c1 c2 + a1 c2^2 + 2 a2 b2 e1 + 
     2 a2 b1 e2 + 2 a1 b2 e2 + 2 c2 e2 f1 + 2 c2 e1 f2 + 2 c1 e2 f2, 
   b^3 + 6 b e f == 
    b1 b2^2 + 2 a2 b2 c1 + 2 a2 b1 c2 + 2 a1 b2 c2 + a2^2 e1 + 
     2 a1 a2 e2 + c2^2 f1 + 2 b2 e2 f1 + 2 c1 c2 f2 + 2 b2 e1 f2 + 
     2 b1 e2 f2, 
   0 == 2 a2 b1 b2 + a1 b2^2 + a2^2 c1 + 2 a1 a2 c2 + 2 b2 c2 f1 + 
     2 a2 e2 f1 + 2 b2 c1 f2 + 2 b1 c2 f2 + 2 a2 e1 f2 + 2 a1 e2 f2, 
   3 b^2 f + 3 e f^2 == 
    a2^2 b1 + 2 a1 a2 b2 + b2^2 f1 + 2 a2 c2 f1 + 2 b1 b2 f2 + 
     2 a2 c1 f2 + 2 a1 c2 f2 + 2 e2 f1 f2 + e1 f2^2, 
   0 == a1 a2^2 + 2 a2 b2 f1 + 2 a2 b1 f2 + 2 a1 b2 f2 + 2 c2 f1 f2 + 
     c1 f2^2, 3 b f^2 == a2^2 f1 + 2 a1 a2 f2 + 2 b2 f1 f2 + b1 f2^2, 
   0 == 2 a2 f1 f2 + a1 f2^2, f^3 == f1 f2^2}

NSolve[eq//n, {f, f1, f2, e, e1, e2, 
   a1, a2, b, b1, b2, c1, c2}]

On my PC, although it is still running, the requested memory remains at about 1.5 GB.

Another idea: define a reasonable subset of equations an try to solve these first.

Best regards,
Wolfgang




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