On Thu, May 14, 2009 at 4:59 AM, John Cremona wrote: > > This debate has been going on for as long as computers have been in > existence. Yes, there is a case to be made the odd roots of negative > reals should return a negative real instead of the "principal" complex > root. But that leads to more subtle problems in other places.
Granted. Choose your poison. > If all of mathematica, maple and matlab do the "non-obvious thing" > there must be a good reason for it! There is but I think these reasons do not necessarily apply to Sage. > And as Mike said, you can always get the > real root by inserting brackets. > ??? Consider the problem to define f(x) = x^(1/3) so that it takes the real branch for x < 0. The best I have been able to come up with so far is: sage: f = lambda x: RealField(53)(x).sign()*(RealField(53)(x).sign()*x)^(1/3) sage: plot(f,(-2,2)) I think there should be a more obvious way. Regards, Bill Page. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
