Le mardi 24 mai 2011 à 12:28 -0500, Andy Ray Terrel a écrit : > On Tue, May 24, 2011 at 11:42 AM, Robert Kern <robert.k...@gmail.com> wrote: > > On Tue, May 24, 2011 at 10:44, Vinzent Steinberg > > <vinzent.steinb...@googlemail.com> wrote: > >> On 24 Mai, 05:08, Matthew <mrock...@gmail.com> wrote: > >>> You're right - it's unclear if this should be an event or a random > >>> variable. Thanks for the heads up on 'or'. I was hoping to use | for > >>> 'given' in the future. I'll figure this out when I get there. Isn't > >>> '==' ok to use though? Isn't it __eq__? I thought that 'is' was the > >>> forbidden one. > >> > >> '==' is forbidden too, because it is Python equality and not > >> mathematical equality. E.g. in Python: > >> > >>>>> (x + 1)**2 == x**2 + 2*x + 1 > >> False > > > > Note that what Vinzent and Ronan mean is not that *Python* forbids > > overriding __eq__ to return other objects. numpy, SQLAlchemy, and > > several other libraries do that just fine. Rather, sympy has decided, > > as a matter of *policy*, to define __eq__ methods in such a way as to > > return a bool, like most other types, in order to allow sympy objects > > to be used in a variety of contexts like most Python objects you will > > encounter. In particular, most sympy objects can be used as dictionary > > keys or set members. > > You can use the relationals instead: > > In [3]: sympy.Eq(x, 2*y) > Out[3]: x == 2*y >
You will probably have to deal with issue 1887, though. http://code.google.com/p/sympy/issues/detail?id=1887 -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com. To unsubscribe from this group, send email to sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
