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from sympy.core import AtomicExpr, Symbol, S |
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from sympy.core.sympify import _sympify |
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from sympy.printing.pretty.stringpict import prettyForm |
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from sympy.printing.precedence import PRECEDENCE |
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from sympy.core.kind import NumberKind |
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class BaseScalar(AtomicExpr): |
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""" |
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A coordinate symbol/base scalar. |
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Ideally, users should not instantiate this class. |
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""" |
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kind = NumberKind |
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def __new__(cls, index, system, pretty_str=None, latex_str=None): |
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from sympy.vector.coordsysrect import CoordSys3D |
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if pretty_str is None: |
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pretty_str = "x{}".format(index) |
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elif isinstance(pretty_str, Symbol): |
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pretty_str = pretty_str.name |
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if latex_str is None: |
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latex_str = "x_{}".format(index) |
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elif isinstance(latex_str, Symbol): |
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latex_str = latex_str.name |
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index = _sympify(index) |
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system = _sympify(system) |
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obj = super().__new__(cls, index, system) |
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if not isinstance(system, CoordSys3D): |
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raise TypeError("system should be a CoordSys3D") |
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if index not in range(0, 3): |
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raise ValueError("Invalid index specified.") |
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obj._id = (index, system) |
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obj._name = obj.name = system._name + '.' + system._variable_names[index] |
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obj._pretty_form = '' + pretty_str |
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obj._latex_form = latex_str |
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obj._system = system |
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return obj |
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is_commutative = True |
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is_symbol = True |
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@property |
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def free_symbols(self): |
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return {self} |
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_diff_wrt = True |
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def _eval_derivative(self, s): |
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if self == s: |
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return S.One |
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return S.Zero |
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def _latex(self, printer=None): |
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return self._latex_form |
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def _pretty(self, printer=None): |
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return prettyForm(self._pretty_form) |
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precedence = PRECEDENCE['Atom'] |
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@property |
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def system(self): |
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return self._system |
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def _sympystr(self, printer): |
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return self._name |
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