On 11/21/2013 8:34 AM, Hugo Coolens wrote:
> I found the following in the documentation:
> sqrt (x^2);
> gives abs(x)
Mathematically speaking this is false and the result given
by Maxima can lead to errors. There are two square roots.
abs(x) is not one of them, as you can see by plotting x, -x, and abs(x).
>
> However:
>
> sqrt(x^4-2*x^2+1);
>
> does not result in
> abs(x^2-1)
This too is false.
> but leaves the expression untouched.
>
>
> It puzzles me why, can I make Maxima do it?
You can try radcan(%), which returns one of the roots, x^2-1,and ignores
the other.
This is a feature of radcan. It shouldn't be a feature of the general
simplifier.
You can try map(factor,%) which returns the dubious abs(x-1)*abs(x+1).
RJF