What is the family of equations you are solving? If they are all of some
common generic form (with parameters), perhaps you could solve them
generically, and write a simple program to solve specific cases in the form
you prefer. Your example is really just x*(quadratic), which makes the
problem extremely simple.
-s
On Fri, Apr 27, 2012 at 06:16, Wilhelm Haager
<wilhelm.haager at htlstp.ac.at>wrote:
> Hi!
>
> Solving the equation
>
> solve(a*x**3+x*(1-x**2)=0,x);
>
> gives imaginary results:
>
> [x = -%i/sqrt(a-1),x = %i/sqrt(a-1),x = 0]
>
> I would like to have the results in the following form, i.e. real:
>
> [x = -1/sqrt(1-a),x = 1/sqrt(1-a),x = 0]
>
> assume(a<1) gives the desired result, but I require real solutions in
> automated calculations
> where I cannot make any assumptions in advance.
> Before the equation is solved, I cannot see what I have to assume.
>
> Is there a simple way (without subsequent maps and other tricky
> transformations) to enforce that?
> (algsys with realonly=true does not work in the desired way).
>
> Thanks in advance
> Wilhelm Haager
>
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