How should existing functions be overridden for new symbols?

[Michael O'Connor]

Hi,

I'm quite new to Sympy, so this is probably simple, but I couldn't find it in the documentation.  The documentation does a good job of explaining how you can define a new function, and specify how it should reduce on certain arguments.  But I couldn't see how to define new symbols and declare how they should act with respect to +, *, **, ...

For example, I was thinking of trying to implement ordinal arithmetic.  In that case, I would have, for example, new symbols omega and epsilon0, and would like omega**epsilon0 to evaluate to epsilon0.  Can that be accomplished?

Thanks!

[Aaron Meurer]

You should subclass Expr and define certain methods. For **, you
should define _eval_power(self, expt) on the omega object.

For + and *, there are no direct ways to interface with Add and Mul,
but you can define __add__ and __mul__ to define the Python operators
directly.

Aaron Meurer

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[Michael O'Connor]

Thank you!