On Jan 27, 2008 6:50 PM, Peter <[EMAIL PROTECTED]> wrote: > > Hi, > > It seems the __abs__ method for vectors is missing the part that is > supposed to square the components before they are added. > > [e.g. abs(vector([1..5])) should really be > sqrt(1+4+9+16+25)=sqrt(55) ] > > The code of the current version is included below. > > def __abs__(self): > """ > Return the square root of the sum of the squares of the > entries of this vector. > > EXAMPLES: > sage: v = vector([1..5]); abs(v) > sqrt(15) > sage: v = vector(RDF, [1..5]); abs(v) > 3.87298334621 > """ > return sum(self.list()).sqrt() > > The last line should be something like > > return sum([x*x for x in self.list()]).sqrt() > > (not sure if that is the most efficient way).
Thanks for tracking this down. I've made it trac #1955 http://trac.sagemath.org/sage_trac/ticket/1955 and declared it a blocker, since obviously it will give terribly wrong mathematical results. William --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
