On Wednesday, August 5, 2020 at 12:49:37 PM UTC-7, NicoJG wrote: > > @rjf Isn't the square root defined to be positive? > Sure: x^2=y <=> x=+/-sqrt(y) > But I think you would never consider f(x):=sqrt(x) to have the codomain of > all negative numbers. >
With complex numbers, there's no concept of negative numbers. A choice of principal branch of sqrt indeed selects only half on the complex plane, but it's not at all clear which choice is most appropriate. Both upper half plane and right half plane have their uses. > At least I would expect a CAS to interpret a square root to be positive. > Certainly not in a complex setting. That's actually one of the main things that "domain: complex" vs. "domain: real" changes in maxima. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/be0d6066-2ebc-4979-aa4c-540f0d7d57b6o%40googlegroups.com.
