Hi Lorenzo, the strange behaviour of round() is explained in the documentation:
sage: u.round? ... This method evaluates an expression in "RR" first and rounds the result. This may lead to misleading results. sage: RR(u).round() 207855083711803936 sage: RealField(100)(u).round() 207855083711803945 Paul Zimmermann -- 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 URL: http://www.sagemath.org