28 lines
909 B
Python
28 lines
909 B
Python
"""
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Naturalunit system.
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The natural system comes from "setting c = 1, hbar = 1". From the computer
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point of view it means that we use velocity and action instead of length and
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time. Moreover instead of mass we use energy.
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"""
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from sympy.physics.units import DimensionSystem
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from sympy.physics.units.definitions import c, eV, hbar
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from sympy.physics.units.definitions.dimension_definitions import (
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action, energy, force, frequency, length, mass, momentum,
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power, time, velocity)
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from sympy.physics.units.prefixes import PREFIXES, prefix_unit
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from sympy.physics.units.unitsystem import UnitSystem
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# dimension system
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_natural_dim = DimensionSystem(
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base_dims=(action, energy, velocity),
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derived_dims=(length, mass, time, momentum, force, power, frequency)
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)
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units = prefix_unit(eV, PREFIXES)
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# unit system
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natural = UnitSystem(base_units=(hbar, eV, c), units=units, name="Natural system")
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