| 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 |
| from sympy.core.kind import NumberKind |
|
|
|
|
| class BaseScalar(AtomicExpr): |
| """ |
| A coordinate symbol/base scalar. |
| |
| Ideally, users should not instantiate this class. |
| |
| """ |
|
|
| kind = NumberKind |
|
|
| 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.") |
| |
| 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 |
|
|
