Clearly Robert has found a bug in maxima. Here's a little test further to my earlier "puzzle": If I write in sage as follows: #$is (equal(-(_SAGE_VAR_r13^2*_SAGE_VAR_r23-_SAGE_VAR_r23^3)/((-_SAGE_VAR_r23^4)+2*_SAGE_VAR_r13^2*_SAGE_VAR_r23^2-_SAGE_VAR_r13^4+_SAGE_VAR_r12^4),0))$
var('r12 r13 r23',domain='complex') assume(r12>0, r13>0, r23>0) #trace( "bool(-(r13^2*r23-r23^3)/((-r23^4)+2*r13^2*r23^2-r13^4+r12^4) == 0)" ) bool(-(r13^2*r23-r23^3)/((-r23^4)+2*r13^2*r23^2-r13^4+r12^4) == 0) then sage finishes without error! Instead, it returns "False". Dropping into pydb, I recover the identical *statement* being shipped off to Maxima! > /home/rllozes/sage-8.0/local/lib/python2.7/site-packages/sage/interfaces/maxima_lib.py(452)_eval_line() 450 line = line[ind_semi+1:] 451 if statement: 5-> 452 result = ((result + '\n') if result else '') + max_to_string(maxima_eval("#$%s$"%statement)) 453 else: 454 statement = line[:ind_dollar] ipdb> p statement 'is (equal(-(_SAGE_VAR_r13^2*_SAGE_VAR_r23-_SAGE_VAR_r23^3)/((-_SAGE_VAR_r23^4)+2*_SAGE_VAR_r13^2*_SAGE_VAR_r23^2-_SAGE_VAR_r13^4+_SAGE_VAR_r12^4),0))' This behavior is independent of whether the variables are declared 'real' or 'complex'. Conclusion: something else is going on in manifolds and/or in maxima. Robert, what version of maxima did you test? - Richard -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.