add read me

venv/lib/python3.12/site-packages/sympy/physics/quantum/constants.py

@@ -0,0 +1,59 @@
+"""Constants (like hbar) related to quantum mechanics."""
+
+from sympy.core.numbers import NumberSymbol
+from sympy.core.singleton import Singleton
+from sympy.printing.pretty.stringpict import prettyForm
+import mpmath.libmp as mlib
+
+#-----------------------------------------------------------------------------
+# Constants
+#-----------------------------------------------------------------------------
+
+__all__ = [
+    'hbar',
+    'HBar',
+]
+
+
+class HBar(NumberSymbol, metaclass=Singleton):
+    """Reduced Plank's constant in numerical and symbolic form [1]_.
+
+    Examples
+    ========
+
+        >>> from sympy.physics.quantum.constants import hbar
+        >>> hbar.evalf()
+        1.05457162000000e-34
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Planck_constant
+    """
+
+    is_real = True
+    is_positive = True
+    is_negative = False
+    is_irrational = True
+
+    __slots__ = ()
+
+    def _as_mpf_val(self, prec):
+        return mlib.from_float(1.05457162e-34, prec)
+
+    def _sympyrepr(self, printer, *args):
+        return 'HBar()'
+
+    def _sympystr(self, printer, *args):
+        return 'hbar'
+
+    def _pretty(self, printer, *args):
+        if printer._use_unicode:
+            return prettyForm('\N{PLANCK CONSTANT OVER TWO PI}')
+        return prettyForm('hbar')
+
+    def _latex(self, printer, *args):
+        return r'\hbar'
+
+# Create an instance for everyone to use.
+hbar = HBar()