Bonjour Thierry, Could you post your matrices Prec, M, mfeEast? I am not able to reproduce the problem with change_ring...
Vincent On 08/05/15 09:15, Thierry Dumont wrote: > Hello, > > I have 2 matrices: Prec and M. > >>sage: Prec.parent > Full MatrixSpace of 4 by 4 dense matrices over Rational Field >>sage: M.parent() > Full MatrixSpace of 4 by 4 dense matrices over Rational Field >>sage: Prec.is_symetric() > True > > ok. I also know that Prec is positive. Then, I do: > >>sage: LC=Prec.cholesky() >>sage: LC.parent() > Full MatrixSpace of 4 by 4 dense matrices over Algebraic Field > > This is ok. > > > sage: print LC.list() > [0.004892377274102731?, 0, 0, 0, 0, 0.002329237476562281?, 0, 0, > -0.001531556341905637?, 0, 1/640, 0, 0, -0.0007624219319910414?, 0, > 0.001320553523013307?] > Everyting seems ok. > > > sage: LCt=LC.transpose() > sage: LCt.parent() > Full MatrixSpace of 4 by 4 dense matrices over Algebraic Field > ok! (of course). > > sage: Z=LC*mfeEast*LCt > > sage: Z.parent() > Full MatrixSpace of 4 by 4 dense matrices over Algebraic Field > > This is perfect. > > ------------------------------- > NOW, my problem: > > M1=Z.change_ring(RDF) > > enters an infinite loop.... > ------------------------------ > > For information: > > sage: version() > 'SageMath Version 6.6, Release Date: 2015-04-14' > > sage: print Z.list() > [-921701247242812313477843412582400000/940135272187668275673825470054308951, > 0.7276068751089991?, -0.1831867383804206?, 0.04189076099436858?, > -0.7276068751089991?, > 7537097158939877741566487100/14132057173012271380088361929, > -0.1186331808041865?, -0.001369231431906186?, -0.1831867383804206?, > 0.1186331808041865?, 0.010771471259174368?, -0.07650322439253288?, > -0.04189076099436858?, -0.001369231431906186?, 0.07650322439253288?, > -0.1562464847599110?] > > > Yours! > > t. > -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
