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 > > -- > Robert Kern > > "I have come to believe that the whole world is an enigma, a harmless > enigma that is made terrible by our own mad attempt to interpret it as > though it had an underlying truth." > -- Umberto Eco > > -- > 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. > > -- 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.
