#!/usr/bin/env python
# -*- coding: utf-8 -*-
# ---------------------------------------------------------------------
# Copyright (c) Merchise Autrement [~º/~] and Contributors
# All rights reserved.
#
# This is free software; you can do what the LICENCE file allows you to.
#
'''The standard `physical quantities`_.
.. _physical quantities: \
https://en.wikipedia.org/wiki/International_System_of_Quantities#Base_quantities
'''
from __future__ import (division as _py3_division,
print_function as _py3_print,
absolute_import as _py3_abs_import)
from .meta import (
Dimension,
UNIT,
)
def kilo(v):
return 1000 * v
def centi(v):
return v / 100
def milli(v):
return v / 1000
def micro(v):
return v / 1000000
def nano(v):
return v / (10**9)
[docs]@Dimension.new()
class Length(object):
metre = UNIT
kilometer = km = kilo(metre)
centimeter = cm = centi(metre)
millimeter = mm = milli(metre)
nanometer = nm = nano(metre)
metre = m = Length.m = Length.metre
L = Length
[docs]@Dimension.new
class Time(object):
second = UNIT
millisecond = ms = milli(second)
nanosecond = ns = nano(second)
minute = second * 60
hour = minute * 60
second = s = Time.s = Time.second
T = Time
[docs]@Dimension.new(unit_aliases=('kg', ))
class Mass(object):
kilogram = UNIT
gram = kilogram / 1000
kilogram = kg = Mass.kg
M = Mass
[docs]@Dimension.new(unit_aliases='A')
class ElectricCurrent(object):
ampere = UNIT
milliampere = milli(ampere)
A = ampere = ElectricCurrent.A
I = ElectricCurrent
[docs]@Dimension.new(unit_aliases='K')
class Temperature(object):
kelvin = UNIT
[docs] @classmethod
def from_celcius(cls, val):
'Convert `val` ºC to K'
return (val + 273.15) * cls.kelvin
[docs] @classmethod
def from_fahrenheit(cls, val):
'Convert `val` ºF to K'
return (val + 459.67) * (5 / 9) * cls.kelvin
K = kelvin = Temperature.K
O = Temperature # The actual symbol would be the capital letter Theta: Θ
[docs]@Dimension.new(unit_alias='mol')
class Substance(object):
mole = UNIT
mole = mol = Substance.mol
N = Substance
[docs]@Dimension.new
class Luminosity(object):
candela = UNIT
J = Luminosity
# Derived quantities
Area = L**2
Volume = L**3
Volume.metre_cubic = Volume._unit_
Volume._unitname_ = 'metre_cubic'
Frequency = T**-1
Frequency.Hz = Frequency._unit_
Force = L * M / T**2
assert hasattr(Force, 'metre_kilogram_per_second_squared')
assert Force == L * M * T**-2
Force.Newton = Force.N = Force._unit_
Presure = M / L / T**2
assert hasattr(Presure, 'kilogram_per_metre_per_second_squared')
assert Presure == L**-1 * M * T**-2, 'as defined in Wikipedia'
Presure.Pascal = Presure.Pa = Presure._unit_
Velocity = L / T
Acceleration = L / T**2