__init__(self, coords, coord_funcs, val_func): 

__call__(self, masses, coords): 

@classmethod
position_function(cls, i): 

@classmethod
normal_function(cls, i, j, k): 

@classmethod
mass_function(cls, i): 

@classmethod
distance_function(cls, i, j): 

@classmethod
angle_function(cls, i, j, k): 

@classmethod
dihedral_function(cls, i, j, k, l): 

@classmethod
book_function(cls, i, j, k, l): 

@classmethod
create_symbol_function(cls, sym): 

@classmethod
sorted_vars(cls, vars): 

@classmethod
from_expr(cls, expr):