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Topic: Automatic solving of unprepared polynomial equation systems?
Replies: 9   Last Post: Apr 1, 2013 9:08 AM

 Messages: [ Previous | Next ]
 Nasser Abbasi Posts: 6,677 Registered: 2/7/05
Re: Automatic solving of unprepared polynomial equation systems?
Posted: Mar 31, 2013 4:01 PM

On 3/31/2013 10:24 AM, Axel Vogt wrote:
> On 31.03.2013 16:15, IV wrote:
> > ...
>
> [c1=A*B/C, c2=C*A/D, D=c3-A, C=A-B];
> solve(%, [A, B, C, D]);
>
> Maple 17 solves it, using roots of a cubic (and ignoring
> cases where a denominatror may vanish).
>
>

Mathematica V 9.01 solves it as well. But D and A are
reserved. So changed them to lower cases.

---------------------------
eq1 = c1 == A*B/c;
eq2 = c2 == c*A/d;
eq3 = d == c3 - A;
eq4 = c == A - B;
Solve[{eq1, eq2, eq3, eq4}, {A, B, c, d}]
----------------------------

The answer is too long to post here.

Reduce can be attempted also here:

Reduce[{eq1, eq2, eq3, eq4}, {A, B, c, d}]

"Reduce reduces the statement by solving equations or inequalities for
vars and eliminating quantifiers."

http://12000.org/tmp/033113/solve.png

--Nasser

Date Subject Author
3/31/13 IV
3/31/13 Axel Vogt
3/31/13 Nasser Abbasi
3/31/13 Axel Vogt
3/31/13 Scott Berg
3/31/13 Rouben Rostamian
3/31/13 Peter Pein
3/31/13 Waldek Hebisch
4/1/13 IV
4/1/13 Robert Lewis