You may want to try charsets, to simplify the equations.
Boris Gaertner wrote:
> "Oguz Bayrak" asked:
>
> > I have 16 equations and I want to substitude them into another 6
> > equations.I would realy be pleased if you can help me with an idea or
> > with a source code or a demo.
> >
> This question is still not answered - perhaps because it is not
> very precisely posed.
>
> To perform multiple substitutions at a time, you may wish to
> consider the function SUBLIS. For substitution of one
> expression you can also use SUBST or the more powerful
> RATSUBST, which is sometimes quite time consuming.
>
> The crucial question is in what form you have the 16
> equations. Substitution is easy if these 16 equations are
> explicit in 16 variables that you use in the 6 equations that
> you wish to transform by a substitution.
>
> sublis ([x=16*sin(t), y=8*cos(t)], z*x = (t*y)^2);
>
> Here you have a list of two equations that are explicit in
> the variables that you want to replace in one given expression.
> That is easy, and it works also when the second argument
> of SUBLIS is a list of equations.
> (A list is also an expression, so it has to work!)
>
> If you cannot isolate the variables that you want to replace in
> your six equations, the situation is *much* more difficult -
> I think you should then try to use SCSIMP
> (do example(scsimp) for a short demo),
> Simplification with constraints is sometimes done with
> Groebner bases, but we do not currently have a good
> package to compute groeber bases.
>
> If this does not help, I think you should tell us more about your
> problem.
>
> Greetings, Boris
>
>
>
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