alt Hacker Newsfor arbitrary complex values sqrt() gives 2 answers with +- signs
so sqrt(square(-i)) = +-i, one of which is x
Replies
Armisael16 • yesterday at 4:18 PM
The sqrt function returns the principle square root, not both. That’s true for all numbers, positive, negative, and complex alike.
I've never seen a CAS that gives two answers for sqrt. Mathematica doesn't, sympy doesn't, and IIRC Maxima also doesn't.