Derivative.expr must be parenthesized when printed

[mcpl-sympy]

Here is an example:

from sympy import Derivative, Function
from sympy.abc import x
f = Function('f')
g = Function('g', commutative=False)
### These two result are printed identically
Derivative(f(x), x) * g(x)
Derivative(f(x)*g(x), x)

Thus, I suggest that Derivative.expr be parenthesized with PRECEDENCE['Mul'] when printed.

[mohitacecode]

I don't think so because when you replace f(x) and g(x) with some expression then both Derivative(f(x), x) * g(x) and Derivative(f(x)*g(x), x) will evaluate diffrently.

They just look same in this case but they are not same.
For example:
f(x) = x2, g(x) = x3

[gschintgen]

I can't reproduce this issue in isympy (outputs are parenthesized), but in a Jupyter notebook with MathJax this is indeed an issue. (Without the commutative=False, the factor g(x) is put in front and there's no ambiguity.)

@mohitacecode :

They just look same in this case but they are not same.

And that's why this is an issue!

[oscarbenjamin]

The problem is the latex printer (isympy uses the pretty printer):

In [58]: d1 = Derivative(f(x)*g(x), x)                                                                                                         

In [59]: d2 = Derivative(f(x), x) * g(x)                                                                                                       

In [60]: d1                                                                                                                                    
Out[60]: 
d            
──(f(x)⋅g(x))
dx           

In [61]: d2                                                                                                                                    
Out[61]: 
d            
──(f(x))⋅g(x)
dx           

In [62]: latex(d1)                                                                                                                             
Out[62]: '\\frac{d}{d x} f{\\left(x \\right)} g{\\left(x \\right)}'

In [63]: latex(d2)                                                                                                                             
Out[63]: '\\frac{d}{d x} f{\\left(x \\right)} g{\\left(x \\right)}'

In [64]: latex(d1) == latex(d2)                                                                                                                
Out[64]: True