On 10/13/2010 12:16 PM, egc wrote:
> After 15+ years of using Maple, I've decided to take latest build of
> Maxima for a spin (motivated to some degree by the desire to find a
> symbolic algebra program I can have my students use at no cost). I've
> done a a bit of 'fooling' with Maxima (learn by doing), and am stuck
> on something which seems pretty trivial.
>
> Consider f : -x^3+x+0.25=0
>
> Now, I know from Maple that the roots of this polynomial are -0.83757,
> -0.26959, and 1.1072.
Actually, those are only approximations to the roots.
> However, in Maxima, if I try
>
> solve(f,x);
>
> I get something is is bizarrely large and convoluted -- all sorts of
> fractions, and square roots, and the like. I tried toggling different
> levels of float, but I still don't end up with a nice simple solution
> vector containing these three solutions.
try
%,rectform;
%,numer;
to get a numeric approximation starting from the exact symbolic answer
to the cubic.
>
> Pointers to the obvious solution?
That would be allroots(f); the rest is just jerking you around a
little. Sorry. :)