On Wed, May 7, 2008 at 8:23 AM, Carlo Hamalainen <[EMAIL PROTECTED]> wrote: > > Hi, > > I think this is a bug. Solving x == y mod 3 works fine: >
That's definitely a bug. We are tracking it here: http://trac.sagemath.org/sage_trac/ticket/3124 > sage: var('x,y') > (x, y) > sage: solve_mod([x == y], 3) > [(0, 0), (1, 1), (2, 2)] > > But solving mod 2 blows up: > > > sage: solve_mod([x == y], 2) > --------------------------------------------------------------------------- > <type 'exceptions.TypeError'> Traceback (most recent call last) > > /home/carlo/work/sagestuff/<ipython console> in <module>() > > /home/carlo/sage/local/lib/python2.5/site-packages/sage/calculus/equations.py > in solve_mod(eqns, modulus) > 1339 S = MPolynomialRing(R, len(vars), vars) > 1340 eqns_mod = [S(eq) if is_SymbolicExpression(eq) else \ > -> 1341 S(eq.lhs() - eq.rhs()) for eq in eqns] > 1342 > 1343 ans = [] > > > /home/carlo/sage/local/lib/python2.5/site-packages/sage/rings/polynomial/multi_polynomial_ring.py > in __call__(self, x, check) > 380 > 381 elif hasattr(x, '_polynomial_'): > --> 382 return x._polynomial_(self) > 383 > 384 elif isinstance(x, str) and x in self.variable_names(): > > /home/carlo/sage/local/lib/python2.5/site-packages/sage/calculus/calculus.py > in _polynomial_(self, R) > 1809 if len(sub) == 0: > 1810 try: > -> 1811 return R(B(self)) > 1812 except TypeError: > 1813 if len(vars) == 1: > > > /home/carlo/sage/local/lib/python2.5/site-packages/sage/rings/integer_mod_ring.py > in __call__(self, x) > 574 def __call__(self, x): > 575 try: > --> 576 return integer_mod.IntegerMod(self, x) > 577 except (NotImplementedError, PariError): > 578 return TypeError, "error coercing to finite field" > > /home/carlo/work/sagestuff/integer_mod.pyx in > sage.rings.integer_mod.IntegerMod (sage/rings/integer_mod.c:1731)() > > /home/carlo/work/sagestuff/integer_mod.pyx in > sage.rings.integer_mod.IntegerMod_int.__init__ > (sage/rings/integer_mod.c:10153)() > > /home/carlo/work/sagestuff/integer_ring.pyx in > sage.rings.integer_ring.IntegerRing_class.__call__ > (sage/rings/integer_ring.c:4473)() > > <type 'exceptions.TypeError'>: unable to convert x (=x - y) to an integer > > > > Any ideas? > > -- > Carlo Hamalainen > http://carlo-hamalainen.net > > > > -- William Stein Associate Professor of Mathematics University of Washington http://wstein.org --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com 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 -~----------~----~----~----~------~----~------~--~---
