collect function bug

[ferymi6041]

when you have an expression with partial differential term like w.diff(x, y) the collect function wont work. the solution is time consuming and we have to make w.diff(x, y) a symbol like "john" and do the collect function and after that we have to convert back "john" to w.diff(x, y). please fix this bug in collect function.

[oscarbenjamin]

Can you give example code to demonstrate?

[ferymi6041]

like if you write collect(expr) and expr = w.diff(x, y) * r + w.diff(x, y) * b you will get an error.

[oscarbenjamin]

It is not worth keeping an issue open unless you can give a clear description of the problem.