On May 13, 2009, at 8:49 PM, Bill Page wrote: > On Wed, May 13, 2009 at 11:23 PM, Alex Ghitza wrote: >> >> On Thu, May 14, 2009 at 1:19 PM, Bill Page wrote: >>> >>> On Wed, May 13, 2009 at 10:46 PM, Mike Hansen wrote: >>>> >>>> On Wed, May 13, 2009 at 6:58 PM, Bill Page wrote: >>>>> >>>>> Can someone explain this apparently inconsistent result? >>>> >>>> It's just operator precedence: >>>> >>>> sage: -(2.0^(1/3)) >>>> -1.25992104989487 >>>> sage: (-2.0)^(1/3) >>>> 0.629960524947437 + 1.09112363597172*I >>>> >>> >>> Clear. Thanks. Why this particular root? >>> >> >> I believe that it is the real 3rd root of 2 times the "natural" >> primitive 6th root of 1, i.e. exp(2*pi*i/6). >> > > In most cases (e.g. plot) isn't the real root more desirable?
This is because the branch in which the positive real root is real is taken. We're opting for continuity and consistency with complex numbers. - Robert --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
