On Apr 4, 2009, at 12:55 PM, Kwankyu wrote: > Hi, > > I get this: > > sage: R=IntegerModRing(8) > sage: m=matrix(R,2,[2,1,3,3]);m.det() > sage: m.inverse() > Traceback (most recent call last): > ... > TypeError: self must be an integral domain. > sage: m^-1 > Traceback (most recent call last): > ... > TypeError: self must be an integral domain. > > Actually, R(3)^-1 produces an error message. I use Sage 3.4. Is > someone implementing the inverse operation in integer mod rings?
You could try lifting, computing the inverse there, then reducing. sage: m.change_ring(ZZ).inverse().change_ring(R) [1 5] [7 6] sage: m.change_ring(ZZ).inverse().change_ring(R) * m [1 0] [0 1] The problem is that the inverse is typically defined over the fraction field, and so it must be an integral domain to have one. - 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 -~----------~----~----~----~------~----~------~--~---
