On Tue, 9 Feb 2021 at 23:58, S.Y. Lee <sylee...@gmail.com> wrote: > > I was not very fond for defining sympy Add, Mul, Pow or Function application > for equation object because I don't think that the algebra of equation looks > well unifiable with other mathematical objects like Expr at the first glance, > And I think that it's important to introduce Add, Mul, Pow, or function > application for Expr or at least the mathematical objects that are > conceptually unifiable with Expr. > We automatically arrive to a conclusion that we need to define unevaluated > sympy functions like `Add(eq1, eq2, evaluate=False)`, `sin(eq, > evaluate=False)`, once we define how to define function application for them.
The suggestion is not to define Add, Mul or Pow for equation arguments. The suggestion is that the Python operators +, *, ** can be used with equations. They should never result in an unevaluated Add though and I would expect Add(eq1, eq2) to raise an error. One of the contentious parts of the proposal is being able to do Function(eq) (e.g. cos(eq)) and that part I also object to. There are many different classes in sympy that use operators like +, * etc without being Expr. > And we would also arrive in questions like: If equation brings its own > algebra system, there should be an equation of equations? How should we solve > them? It's not an "algebra system": it's just a few convenience operations. It should not be confused with allowing Equation to be used in places where Expr is expected. -- Oscar -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAHVvXxQ4pQL%3DkLTGyWCa2Z3HzayzFyiJOv_yJSXtTbu%3D9CgjmQ%40mail.gmail.com.
