Simplifying sqrt(4*z^2-4*z+1)?

Richard Fateman wrote:
> radcan assumes |z| --> inf, so your assumption that |z|<1/2 won't work.
> Maybe here's a workaround.
>
> ratsubst(1/z,w,radcan(subst(1/w,z, expression)));
>
> RJF
>   
Not quite.  first you have to set radexpand:false.  The default setting 
is, in my opinion, a recipe for disaster.
RJF