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)
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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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