Is there a way I can rewrite an

`Expr`

as `pde`

using `_eval_rewrite_as_pde`

?
i think rewrite lets you pass string arguments, which would let you do something like that

so it'd be something like expr.rewrite('pde')

I was trying expr.rewrite(sin) :(

And how we do we declare a multivariate function?

For e.g.

I've to represent its partial derivative with respect to

For e.g.

`E(x, t)`

.I've to represent its partial derivative with respect to

`x`

and `t`

.
can we do E = Function('x, t')

And when I pass E in the Derivative class

x and t should be aware of that.

you'd declare

`f = Function('f')`

or `f = symbols('f', function=True)`

then you do

`f(x,t)`

the argument to

`Function`

is the name of the function, not the arguments
*not the arguments of the function

It was very silly