Hello, If you want to use numerical linear algebra, you should use matrices over the RealDoubleField (RDF) as no one as done work on arbitrary precision numerical linear algebra (which is what is being used when you just use 0.91).
sage: M= Matrix([[1,0,0],[0,1,0],[0,0,1]]) sage: M = 0.91*M.change_ring(RDF); M [0.91 0.0 0.0] [ 0.0 0.91 0.0] [ 0.0 0.0 0.91] sage: M.parent() Full MatrixSpace of 3 by 3 dense matrices over Real Double Field sage: M*M.inverse() [1.0 0.0 0.0] [0.0 1.0 0.0] [0.0 0.0 1.0] Notice that sage: (0.91).parent() Real Field with 53 bits of precision sage: Matrix([[1,0,0],[0,1,0],[0,0,1]])*0.91 [0.910000000000000 0.000000000000000 0.000000000000000] [0.000000000000000 0.910000000000000 0.000000000000000] [0.000000000000000 0.000000000000000 0.910000000000000] sage: _.parent() Full MatrixSpace of 3 by 3 dense matrices over Real Field with 53 bits of precision which is different that the above. --Mike --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
