Is there a way to specify x!=y in a piecewise function in python?

Question

I am sort of new in this whole word, and today I wanted to try and do some maths on jupyter notebook. I wanted to solve this function: enter image description here

I am using jupyter notebook, and modules like sympy, numpy and matplotlib, but I don't know how to represent the x!=-y.

For example, if instead of x!=-y, the function was x>y I will do:

 x, y = sp.symbols('x y', real=True)
 g = sp.Piecewise(((x*y**4 - x**4*y)/(x**3+y**3), (x>y)), (0, True)) 
 G = sp.Lambda((x,y), g)
 display(G(x,y))

But if I type x!=-y, it doesn't work (it doesn't display the whole piecewise function, it only displays the 'first part' of the piecewise funtion), and I don't know how to solve it.

Thanks!!!

Answer 1

With SymPy we can only create equality with Eq and non-equality with Ne. That's because in SymPy == and != are reserved for structural comparison of symbolic expressions.

So, in your example you would have to do:

x, y = symbols('x y', real=True)
g = Piecewise(((x*y**4 - x**4*y)/(x**3+y**3), Ne(x, -y)), (0, True)) 
display(g)