This is from the notebook's "report a problem" bugtracker, there are *two* different problems reported. Machine is Linux/32bit on Sage 4.0.2.
Quote: different formatting of output of eigenvectors_left depending on which space the matrix is over A = matrix(QQ,3,3,range(9)) B = matrix(RDF,3,3,range(9)) A.eigenvectors_left() [(0, [ (1, -2, 1) ], 1), (-1.348469228349535?, [(1, 0.3101020514433644?, -0.3797958971132713?)], 1), (13.34846922834954?, [(1, 1.289897948556636?, 1.579795897113272?)], 1)] i.e. a list (eigenvalue, [corresponding eigenspace], multiplicity) whereas B.eigenvectors_left() ([13.3484692283, -1.34846922835, -1.1327908706e-15], [ 0.440242867236 0.567868371314 0.695493875393] [ 0.897878732262 0.278434036822 -0.341010658618] [ 0.408248290464 -0.816496580928 0.408248290464]) i.e. a list of eigenvalues and then a matrix whose rows are the eigenvectors this is a bit confusing and it would be nicer if the output formatting was the same in both cases. ******************* second one: ******************* Also, I noticed that the eigenvalues for the matrix over RDF are a bit inaccurate, leading to very different eigenvectors. Using B.charpoly.roots() [(-1.34846922835, 1), (0.0, 1), (13.3484692283, 1)] the zero eigenvalue is actually zero could the output of the eigenvectors_left method be standardised over the different fields? (same goes for eigenvectors_right, of course) About the values of eigenvalues and -vectors, is that an intrinsic problem with using RDF or can it be improved? --~--~---------~--~----~------------~-------~--~----~ 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-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
