You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
70 lines
1.9 KiB
70 lines
1.9 KiB
from sympy.core import AtomicExpr, Symbol, S
|
|
from sympy.core.sympify import _sympify
|
|
from sympy.printing.pretty.stringpict import prettyForm
|
|
from sympy.printing.precedence import PRECEDENCE
|
|
|
|
|
|
class BaseScalar(AtomicExpr):
|
|
"""
|
|
A coordinate symbol/base scalar.
|
|
|
|
Ideally, users should not instantiate this class.
|
|
|
|
"""
|
|
|
|
def __new__(cls, index, system, pretty_str=None, latex_str=None):
|
|
from sympy.vector.coordsysrect import CoordSys3D
|
|
if pretty_str is None:
|
|
pretty_str = "x{}".format(index)
|
|
elif isinstance(pretty_str, Symbol):
|
|
pretty_str = pretty_str.name
|
|
if latex_str is None:
|
|
latex_str = "x_{}".format(index)
|
|
elif isinstance(latex_str, Symbol):
|
|
latex_str = latex_str.name
|
|
|
|
index = _sympify(index)
|
|
system = _sympify(system)
|
|
obj = super().__new__(cls, index, system)
|
|
if not isinstance(system, CoordSys3D):
|
|
raise TypeError("system should be a CoordSys3D")
|
|
if index not in range(0, 3):
|
|
raise ValueError("Invalid index specified.")
|
|
# The _id is used for equating purposes, and for hashing
|
|
obj._id = (index, system)
|
|
obj._name = obj.name = system._name + '.' + system._variable_names[index]
|
|
obj._pretty_form = '' + pretty_str
|
|
obj._latex_form = latex_str
|
|
obj._system = system
|
|
|
|
return obj
|
|
|
|
is_commutative = True
|
|
is_symbol = True
|
|
|
|
@property
|
|
def free_symbols(self):
|
|
return {self}
|
|
|
|
_diff_wrt = True
|
|
|
|
def _eval_derivative(self, s):
|
|
if self == s:
|
|
return S.One
|
|
return S.Zero
|
|
|
|
def _latex(self, printer=None):
|
|
return self._latex_form
|
|
|
|
def _pretty(self, printer=None):
|
|
return prettyForm(self._pretty_form)
|
|
|
|
precedence = PRECEDENCE['Atom']
|
|
|
|
@property
|
|
def system(self):
|
|
return self._system
|
|
|
|
def _sympystr(self, printer):
|
|
return self._name
|