This is now Ticket #4273 on trac (http://trac.sagemath.org/sage_trac/ ticket/4273).
I will try to fix this if no one else does. Many Sage developers are busy at Sage Days 10 in Nancy, France, so they might be a little more distracted than usual, but I think this is a major bug so it should get attention soon. -M. Hampton On Oct 12, 10:39 pm, Marshall Hampton <[EMAIL PROTECTED]> wrote: > The transformation=True fails even for matrix(QQ,[[0,1,0],[0,0,0], > [0,0,0]]). It looks like the algorithm to construct it is flawed, and > will not work if there are blocks with the same eigenvalue. Anyone > want to re-write this? > > -M. Hampton > > On Oct 12, 9:34 pm, Rob Beezer <[EMAIL PROTECTED]> wrote: > > > I have a 6x6 matrix with integer entries, whose eigenvalues are also > > integers. I wanted the Jordan canonical form, and the associated > > matrix to make the similarity transformation. The Jordan form comes > > out nicely, but I can't get the transformation matrix. I've included > > the error output below - the error seems more severe without setting > > base_ring=QQ. I've also include a legitimate transformation matrix I > > worked up by hand (with some help from SAGE!). > > > Is this expected behavior? Any usage hints or workarounds? Thanks. > > > Rob > > > m=matrix(QQ, [[2,0,1,1,0,0],[0,2,1,1,0,0],[2,0,1,0,0,1],[2,0,0,1,1,0], > > [0,2,1,0,0,1],[0,2,0,1,1,0]]) > > m.jordan_form() > > > [4|0|0 0|0 0] > > [-+-+---+---] > > [0|2|0 0|0 0] > > [-+-+---+---] > > [0|0|0 1|0 0] > > [0|0|0 0|0 0] > > [-+-+---+---] > > [0|0|0 0|0 1] > > [0|0|0 0|0 0] > > > p=m.jordan_form(base_ring=QQ, transformation=True) > > > Traceback (click to the left for traceback) > > ... > > ValueError: cannot compute the basis of the Jordan block of size 2 > > with > > eigenvalue 0 > > > Traceback (most recent call last): > > File "<stdin>", line 1, in <module> > > File "/home/rob/.sage/sage_notebook/worksheets/admin/46/code/98.py", > > line 6, in <module> > > p=m.jordan_form(base_ring=QQ, transformation=True) > > File "/opt/sage-3.1.2/local/lib/python2.5/site-packages/ > > SQLAlchemy-0.4.6-py2.5.egg/", line 1, in <module> > > File "matrix2.pyx", line 4125, in > > sage.matrix.matrix2.Matrix.jordan_form (sage/matrix/matrix2.c:23429) > > ValueError: cannot compute the basis of the Jordan block of size 2 > > with eigenvalue 0 > > > p=matrix(QQ,[[1,1,0,1,3,1],[1,-1,0,1,3,1],[1,0,1,1,0,1], > > [1,0,-1,-3,-6,0],[1,-2,1,0,0,-8],[1,-2,-1,-2,-6,-3]]) > > p.inverse()*m*p == m.jordan_form() > > > True --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@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-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
