text: r"""
  ==================================
  Constants (:mod:`scipy.constants`)
  ==================================
  
  .. currentmodule:: scipy.constants
  
  Physical and mathematical constants and units.
  
  
  Mathematical constants
  ======================
  
  ================  =================================================================
  ``pi``            Pi
  ``golden``        Golden ratio
  ``golden_ratio``  Golden ratio
  ================  =================================================================
  
  
  Physical constants
  ==================
  
  ===========================  =================================================================
  ``c``                        speed of light in vacuum
  ``speed_of_light``           speed of light in vacuum
  ``mu_0``                     the magnetic constant :math:`\mu_0`
  ``epsilon_0``                the electric constant (vacuum permittivity), :math:`\epsilon_0`
  ``h``                        the Planck constant :math:`h`
  ``Planck``                   the Planck constant :math:`h`
  ``hbar``                     :math:`\hbar = h/(2\pi)`
  ``G``                        Newtonian constant of gravitation
  ``gravitational_constant``   Newtonian constant of gravitation
  ``g``                        standard acceleration of gravity
  ``e``                        elementary charge
  ``elementary_charge``        elementary charge
  ``R``                        molar gas constant
  ``gas_constant``             molar gas constant
  ``alpha``                    fine-structure constant
  ``fine_structure``           fine-structure constant
  ``N_A``                      Avogadro constant
  ``Avogadro``                 Avogadro constant
  ``k``                        Boltzmann constant
  ``Boltzmann``                Boltzmann constant
  ``sigma``                    Stefan-Boltzmann constant :math:`\sigma`
  ``Stefan_Boltzmann``         Stefan-Boltzmann constant :math:`\sigma`
  ``Wien``                     Wien displacement law constant
  ``Rydberg``                  Rydberg constant
  ``m_e``                      electron mass
  ``electron_mass``            electron mass
  ``m_p``                      proton mass
  ``proton_mass``              proton mass
  ``m_n``                      neutron mass
  ``neutron_mass``             neutron mass
  ===========================  =================================================================
  
  
  Constants database
  ------------------
  
  In addition to the above variables, :mod:`scipy.constants` also contains the
  2018 CODATA recommended values [CODATA2018]_ database containing more physical
  constants.
  
  .. autosummary::
     :toctree: generated/
  
     value      -- Value in physical_constants indexed by key
     unit       -- Unit in physical_constants indexed by key
     precision  -- Relative precision in physical_constants indexed by key
     find       -- Return list of physical_constant keys with a given string
     ConstantWarning -- Constant sought not in newest CODATA data set
  
  .. data:: physical_constants
  
     Dictionary of physical constants, of the format
     ``physical_constants[name] = (value, unit, uncertainty)``.
  
  Available constants:
  
  ======================================================================  ====
  %(constant_names)s
  ======================================================================  ====
  
  
  Units
  =====
  
  SI prefixes
  -----------
  
  ============  =================================================================
  ``yotta``     :math:`10^{24}`
  ``zetta``     :math:`10^{21}`
  ``exa``       :math:`10^{18}`
  ``peta``      :math:`10^{15}`
  ``tera``      :math:`10^{12}`
  ``giga``      :math:`10^{9}`
  ``mega``      :math:`10^{6}`
  ``kilo``      :math:`10^{3}`
  ``hecto``     :math:`10^{2}`
  ``deka``      :math:`10^{1}`
  ``deci``      :math:`10^{-1}`
  ``centi``     :math:`10^{-2}`
  ``milli``     :math:`10^{-3}`
  ``micro``     :math:`10^{-6}`
  ``nano``      :math:`10^{-9}`
  ``pico``      :math:`10^{-12}`
  ``femto``     :math:`10^{-15}`
  ``atto``      :math:`10^{-18}`
  ``zepto``     :math:`10^{-21}`
  ============  =================================================================
  
  Binary prefixes
  ---------------
  
  ============  =================================================================
  ``kibi``      :math:`2^{10}`
  ``mebi``      :math:`2^{20}`
  ``gibi``      :math:`2^{30}`
  ``tebi``      :math:`2^{40}`
  ``pebi``      :math:`2^{50}`
  ``exbi``      :math:`2^{60}`
  ``zebi``      :math:`2^{70}`
  ``yobi``      :math:`2^{80}`
  ============  =================================================================
  
  Mass
  ----
  
  =================  ============================================================
  ``gram``           :math:`10^{-3}` kg
  ``metric_ton``     :math:`10^{3}` kg
  ``grain``          one grain in kg
  ``lb``             one pound (avoirdupous) in kg
  ``pound``          one pound (avoirdupous) in kg
  ``blob``           one inch version of a slug in kg (added in 1.0.0)
  ``slinch``         one inch version of a slug in kg (added in 1.0.0)
  ``slug``           one slug in kg (added in 1.0.0)
  ``oz``             one ounce in kg
  ``ounce``          one ounce in kg
  ``stone``          one stone in kg
  ``grain``          one grain in kg
  ``long_ton``       one long ton in kg
  ``short_ton``      one short ton in kg
  ``troy_ounce``     one Troy ounce in kg
  ``troy_pound``     one Troy pound in kg
  ``carat``          one carat in kg
  ``m_u``            atomic mass constant (in kg)
  ``u``              atomic mass constant (in kg)
  ``atomic_mass``    atomic mass constant (in kg)
  =================  ============================================================
  
  Angle
  -----
  
  =================  ============================================================
  ``degree``         degree in radians
  ``arcmin``         arc minute in radians
  ``arcminute``      arc minute in radians
  ``arcsec``         arc second in radians
  ``arcsecond``      arc second in radians
  =================  ============================================================
  
  
  Time
  ----
  
  =================  ============================================================
  ``minute``         one minute in seconds
  ``hour``           one hour in seconds
  ``day``            one day in seconds
  ``week``           one week in seconds
  ``year``           one year (365 days) in seconds
  ``Julian_year``    one Julian year (365.25 days) in seconds
  =================  ============================================================
  
  
  Length
  ------
  
  =====================  ============================================================
  ``inch``               one inch in meters
  ``foot``               one foot in meters
  ``yard``               one yard in meters
  ``mile``               one mile in meters
  ``mil``                one mil in meters
  ``pt``                 one point in meters
  ``point``              one point in meters
  ``survey_foot``        one survey foot in meters
  ``survey_mile``        one survey mile in meters
  ``nautical_mile``      one nautical mile in meters
  ``fermi``              one Fermi in meters
  ``angstrom``           one Angstrom in meters
  ``micron``             one micron in meters
  ``au``                 one astronomical unit in meters
  ``astronomical_unit``  one astronomical unit in meters
  ``light_year``         one light year in meters
  ``parsec``             one parsec in meters
  =====================  ============================================================
  
  Pressure
  --------
  
  =================  ============================================================
  ``atm``            standard atmosphere in pascals
  ``atmosphere``     standard atmosphere in pascals
  ``bar``            one bar in pascals
  ``torr``           one torr (mmHg) in pascals
  ``mmHg``           one torr (mmHg) in pascals
  ``psi``            one psi in pascals
  =================  ============================================================
  
  Area
  ----
  
  =================  ============================================================
  ``hectare``        one hectare in square meters
  ``acre``           one acre in square meters
  =================  ============================================================
  
  
  Volume
  ------
  
  ===================    ========================================================
  ``liter``              one liter in cubic meters
  ``litre``              one liter in cubic meters
  ``gallon``             one gallon (US) in cubic meters
  ``gallon_US``          one gallon (US) in cubic meters
  ``gallon_imp``         one gallon (UK) in cubic meters
  ``fluid_ounce``        one fluid ounce (US) in cubic meters
  ``fluid_ounce_US``     one fluid ounce (US) in cubic meters
  ``fluid_ounce_imp``    one fluid ounce (UK) in cubic meters
  ``bbl``                one barrel in cubic meters
  ``barrel``             one barrel in cubic meters
  ===================    ========================================================
  
  Speed
  -----
  
  ==================    ==========================================================
  ``kmh``               kilometers per hour in meters per second
  ``mph``               miles per hour in meters per second
  ``mach``              one Mach (approx., at 15 C, 1 atm) in meters per second
  ``speed_of_sound``    one Mach (approx., at 15 C, 1 atm) in meters per second
  ``knot``              one knot in meters per second
  ==================    ==========================================================
  
  
  Temperature
  -----------
  
  =====================  =======================================================
  ``zero_Celsius``       zero of Celsius scale in Kelvin
  ``degree_Fahrenheit``  one Fahrenheit (only differences) in Kelvins
  =====================  =======================================================
  
  .. autosummary::
     :toctree: generated/
  
     convert_temperature
  
  Energy
  ------
  
  ====================  =======================================================
  ``eV``                one electron volt in Joules
  ``electron_volt``     one electron volt in Joules
  ``calorie``           one calorie (thermochemical) in Joules
  ``calorie_th``        one calorie (thermochemical) in Joules
  ``calorie_IT``        one calorie (International Steam Table calorie, 1956) in Joules
  ``erg``               one erg in Joules
  ``Btu``               one British thermal unit (International Steam Table) in Joules
  ``Btu_IT``            one British thermal unit (International Steam Table) in Joules
  ``Btu_th``            one British thermal unit (thermochemical) in Joules
  ``ton_TNT``           one ton of TNT in Joules
  ====================  =======================================================
  
  Power
  -----
  
  ====================  =======================================================
  ``hp``                one horsepower in watts
  ``horsepower``        one horsepower in watts
  ====================  =======================================================
  
  Force
  -----
  
  ====================  =======================================================
  ``dyn``               one dyne in newtons
  ``dyne``              one dyne in newtons
  ``lbf``               one pound force in newtons
  ``pound_force``       one pound force in newtons
  ``kgf``               one kilogram force in newtons
  ``kilogram_force``    one kilogram force in newtons
  ====================  =======================================================
  
  Optics
  ------
  
  .. autosummary::
     :toctree: generated/
  
     lambda2nu
     nu2lambda
  
  References
  ==========
  
  .. [CODATA2018] CODATA Recommended Values of the Fundamental
     Physical Constants 2018.
  
     https://physics.nist.gov/cuu/Constants/
  
  """
  # Modules contributed by BasSw (wegwerp@gmail.com)
  from .codata import *
  from .constants import *
  from .codata import _obsolete_constants
  
  _constant_names = [(_k.lower(), _k, _v)
                     for _k, _v in physical_constants.items()
                     if _k not in _obsolete_constants]
  _constant_names = "\n".join(["``%s``%s  %s %s" % (_x[1], " "*(66-len(_x[1])),
                                                    _x[2][0], _x[2][1])
                               for _x in sorted(_constant_names)])
  if __doc__:
      __doc__ = __doc__ % dict(constant_names=_constant_names)
  
  del _constant_names
  
  __all__ = [s for s in dir() if not s.startswith('_')]
  
  from scipy._lib._testutils import PytestTester
  test = PytestTester(__name__)
  del PytestTester
  