Question about "MeshCoordinates()" in legacy FEniCS

[Swani]

Thanks for the quick reply , @dokken!
The purpose of my exploration of the MeshCoordinates() was to convert the legacy DOLFIN code to dolfinx, which does the formula calculation for subdomains for a given mesh.

The code I was working on was similar to the code(conditional equation form) mentioned below,

@andrew16

#p_Ex = Expression('x[0]-x[1] >= 0 ? -2*(exp(x[0]-x[1])-1)/(exp(x[0]-x[1])-1): -(x[0]-x[1])',
#                   degree = 3)

x0, x1 = MeshCoordinates(mesh)

p_Ex = conditional(ge(0, x0-x1), -2*(exp(x0-x1)-1)/(exp(x0-x1)-1), -(x0-x1))

and I wanted to convert this type of code to dolfinx.

You mentioned that MeshCoordinates() was a function that used before SpatialCoordinate(), and after reading that post, I googled clue1(Form compilation) and clue2(conditional.py github), and based on that,

# In dolfinx env. Assuming imported the ufl library beforehand
x0, x1 = SpatialCoordinate(mesh)
p_Ex = conditional(ge(0, x0-x1), -2*(exp(x0-x1)-1)/(exp(x0-x1)-1), -(x0-x1))

I was able to get the desired result when I ran the code in the form below.

An additional question I have is,
are MeshCoordinates() and SpatialCoordinate() the same function?
If SpatialCoordinate() came later, it seems like there would be some differences, then what differences have be…?