Atan2 doesn't symplify as expected.



>Basically, if the user types in n1, 
>> 
>> 
>> (%i19) n1:sqrt(x^4-2*x^2+1); 
>
>
>then he is typing two expressions.  If he means one of them, he should say which one.
>
>It is unlikely he means a function with two corners, don't you think?

Well, maybe you are right about that, I don?t know.
>
>That's what you came up with,   abs(x-1)*ab(x+1).
>
>How can he say which one?  Perhaps by specifying a point,  or by
>simplifying to  x^2-1  or 1-x^2.

Maybe he or she does want to say the non-function which includes both answers and is bi-valued.  Then isn?t is sufficient to say domain:complex?  
I don?t know if the simplification of sqrt(x^2) to abs(x) is a mistake, maybe there should be another flag to use besides domain:complex, since that has other possibly unintended side effects, but another flag would fix that.
Rich