I don't think you should need to call _add_, but this looks like a bug to me:
---------------------------------------------------------------------- | Sage Version 4.7.1, Release Date: 2011-08-11 | | Type notebook() for the GUI, and license() for information. | ---------------------------------------------------------------------- sage: 1+SR(2) 3 sage: 1.__add__(SR(2)) 3 sage: 1._add_(SR(2)) ------------------------------------------------------------------------ Unhandled SIGSEGV: A segmentation fault occurred in Sage. This probably occurred because a *compiled* component of Sage has a bug in it and is not properly wrapped with sig_on(), sig_off(). You might want to run Sage under gdb with 'sage -gdb' to debug this. Sage will now terminate. Similarly for _sub_ and _mul_. _div_ gives a slightly different result: sage: 1._div_(SR(2)) ERROR: An unexpected error occurred while tokenizing input The following traceback may be corrupted or invalid The error message is: ('EOF in multi-line statement', (3258, 0)) ERROR: An unexpected error occurred while tokenizing input The following traceback may be corrupted or invalid The error message is: ('EOF in multi-line statement', (3244, 0)) --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /Users/mcneil/<ipython console> in <module>() /Applications/sage/local/lib/python2.6/site-packages/sage/rings/integer.so in sage.rings.integer.Integer._div_ (sage/rings/integer.c:11866)() /Applications/sage/local/lib/python2.6/site-packages/sage/rings/integer.so in sage.rings.integer.Integer._div_ (sage/rings/integer.c:11824)() /Applications/sage/local/lib/python2.6/site-packages/sage/rings/integer_ring.so in sage.rings.integer_ring.IntegerRing_class._div (sage/rings/integer_ring.c:5158)() TypeError: Argument 'right' has incorrect type (expected sage.rings.integer.Integer, got sage.symbolic.expression.Expression) Doug -- 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