#
# = Physical Constants
#
# The GSL physical constants are defined as Ruby constants under the
# modules
# * <tt>GSL::CONST::MKSA</tt> (MKSA unit)
# * <tt>GSL::CONST:CGSM</tt>  (CGSM unit)
# * <tt>GSL::CONST:NUM</tt>   (Dimension-less constants)
# For example, the GSL C constant
# <tt>GSL_CONST_MKSA_SPEED_OF_LIGHT</tt> is represented by a Ruby constant,
#       GSL_CONST_MKSA_SPEED_OF_LIGHT  ---> GSL::CONST::MKSA::SPEED_OF_LIGHT
#
# The following lists a part of the constants. Most of the constants are
# defined both in the modules <tt>GSL::CONST::MKSA</tt> and <tt>GSL::CONST::CGSM</tt>.
# See also the {GSL reference}[https://gnu.org/software/gsl/manual/gsl-ref_37.html#SEC479]
#
# Contents:
# 1. {Fundamental Constants}[link:const_rdoc.html#label-Fundamental+Constants]
# 1. {Astronomy and Astrophysics}[link:const_rdoc.html#label-Astronomy+and+Astrophysics]
# 1. {Atomic and Nuclear Physics}[link:const_rdoc.html#label-Atomic+and+Nuclear+Physics]
# 1. {Measurement of Time}[link:const_rdoc.html#label-Measurement+of+Time]
# 1. {Imperial Units}[link:const_rdoc.html#label-Imperial+Units]
# 1. {Nautical Units}[link:const_rdoc.html#label-Nautical+Units]
# 1. {Printers Units}[link:const_rdoc.html#label-Printers+Units]
# 1. {Volume}[link:const_rdoc.html#label-Volume]
# 1. {Mass and Weight}[link:const_rdoc.html#label-Mass+and+Weight]
# 1. {Thermal Energy and Power}[link:const_rdoc.html#label-Thermal+Energy+and+Power]
# 1. {Pressure}[link:const_rdoc.html#label-Pressure]
# 1. {Viscosity}[link:const_rdoc.html#label-Viscosity]
# 1. {Light and Illumination}[link:const_rdoc.html#label-Light+and+Illumination]
# 1. {Radioactivity}[link:const_rdoc.html#label-Radioactivity]
# 1. {Force and Energy}[link:const_rdoc.html#label-Force+and+Energy]
# 1. {Prefixes}[link:const_rdoc.html#label-Prefixes]
# 1. {Examples}[link:const_rdoc.html#label-Example]
#
# == Fundamental Constants
# ---
# * GSL::CONST::MKSA::SPEED_OF_LIGHT
#
#   The speed of light in vacuum, c.
# ---
# * GSL::CONST::MKSA::VACUUM_PERMEABILITY
#
#   The permeability of free space, \mu (not defined in GSL::CONST::CGSM).
# ---
# * GSL::CONST::MKSA::VACUUM_PERMITTIVITY
#
#   The permittivity of free space, \epsilon_0 (not defined in GSL::CONST::CGSM).
# ---
# * GSL::CONST::MKSA::PLANCKS_CONSTANT_H
#
#   Planck's constant, <tt>h</tt>.
# ---
# * GSL::CONST::MKSA::PLANCKS_CONSTANT_HBAR
#
#   Planck's constant divided by 2\pi, \hbar.
# ---
# * GSL::CONST::NUM::AVOGADRO
#
#   Avogadro's number
# ---
# * GSL::CONST::MKSA::FARADAY
#
#   The molar charge of 1 Faraday.
# ---
# * GSL::CONST::MKSA::BOLTZMANN
#
#   The Boltzmann constant, k.
# ---
# * GSL::CONST::MKSA::STEFAN_BOLTZMANN_CONSTANT
#
#   The Stefan-Boltzmann constant, \sigma.
# ---
# * GSL::CONST::MKSA::MOLAR_GAS
#
#   The molar gas constant, R_0.
# ---
# * GSL::CONST::MKSA::STANDARD_GAS_VOLUME
#
#   The standard gas volume, V_0.
# ---
# * GSL::CONST::MKSA::GAUSS
#
#   The magnetic field of 1 Gauss.
#
# == Astronomy and Astrophysics
# ---
# * GSL::CONST::MKSA::ASTRONOMICAL_UNIT
#
#   The length of 1 astronomical unit (mean earth-sun distance), AU.
# ---
# * GSL::CONST::MKSA::GRAVITATIONAL_CONSTANT
#
#   The gravitational constant, G.
# ---
# * GSL::CONST::MKSA::LIGHT_YEAR
#
#   The distance of 1 light-year, ly.
# ---
# * GSL::CONST::MKSA::PARSEC
#
#   The distance of 1 parsec, pc.
# ---
# * GSL::CONST::MKSA::GRAV_ACCEL
#
#   The standard gravitational acceleration on Earth, g.
# ---
# * GSL::CONST::MKSA::SOLAR_MASS
#
#   The mass of the Sun.
#
# == Atomic and Nuclear Physics
# ---
# * GSL::CONST::MKSA::ELECTRON_CHARGE
#
#   The charge of the electron, e.
# ---
# * GSL::CONST::CGSM::ELECTRON_CHARGE_ESU
#
#   The charge of the electron, e, in esu unit (not defined in GSL::CONST::MKSA).
# ---
# * GSL::CONST::MKSA::ELECTRON_VOLT
#
#   The energy of 1 electron volt, eV.
# ---
# * GSL::CONST::MKSA::UNIFIED_ATOMIC_MASS
#
#   The unified atomic mass, amu.
# ---
# * GSL::CONST::MKSA::MASS_ELECTRON
#
#   The mass of the electron, m_e.
# ---
# * GSL::CONST::MKSA::MASS_MUON
#
#   The mass of the muon, m_\mu.
# ---
# * GSL::CONST::MKSA::MASS_PROTON
#
#   The mass of the proton, m_p.
# ---
# * GSL::CONST::MKSA::MASS_NEUTRON
#
#   The mass of the proton, m_n.
# ---
# * GSL::CONST::NUM::FINE_STRUCTURE
#
#   The electromagnetic fine structure constant alpha.
# ---
# * GSL::CONST::MKSA::RYDBERG
#
#   The Rydberg constant, Ry, in units of energy. This is related to the Rydberg inverse wavelength R by Ry = h c R.
# ---
# * GSL::CONST::MKSA::THOMSON_CROSS_SECTION
#
#   The Thomson cross section of photon scattering by electrons.
# ---
# * GSL::CONST::MKSA::BOHR_RADIUS
#
#   The Bohr radius, a_0.
# ---
# * GSL::CONST::MKSA::ANGSTROM
#
#   The length of 1 angstrom.
# ---
# * GSL::CONST::MKSA::BARN
#
#   The area of 1 barn.
# ---
# * GSL::CONST::MKSA::BOHR_MAGNETON
#
#   The Bohr Magneton, mu_B.
# ---
# * GSL::CONST::MKSA::NUCLEAR_MAGNETON
#
#   The Nuclear Magneton, mu_N.
# ---
# * GSL::CONST::MKSA::ELECTRON_MAGNETIC_MOMENT
#
#   The absolute value of the magnetic moment of the electron, mu_e. The physical magnetic moment of the electron is negative.
# ---
# * GSL::CONST::MKSA::PROTON_MAGNETIC_MOMENT
#
#   The magnetic moment of the proton, mu_p.
#
# == Measurement of Time
# ---
# * GSL::CONST::MKSA::MINUTE
#
#   The number of seconds in 1 minute.
# ---
# * GSL::CONST::MKSA::HOUR
#
#   The number of seconds in 1 hour.
# ---
# * GSL::CONST::MKSA::DAY
#
#   The number of seconds in 1 day.
# ---
# * GSL::CONST::MKSA::WEEK
#
#   The number of seconds in 1 week.
#
# == Imperial Units
# ---
# * GSL::CONST::MKSA::INCH
#
#   The length of 1 inch.
# ---
# * GSL::CONST::MKSA::FOOT
#
#   The length of 1 foot.
# ---
# * GSL::CONST::MKSA::YARD
#
#   The length of 1 yard.
# ---
# * GSL::CONST::MKSA::MILE
#
#   The length of 1 mile.
# ---
# * GSL::CONST::MKSA::MIL
#
#   The length of 1 mil (1/1000th of an inch).
#
# == Nautical Units
# ---
# * GSL::CONST::MKSA::NAUTICAL_MILE
#
#   The length of 1 nautical mile.
# ---
# * GSL::CONST::MKSA::FATHOM
#
#   The length of 1 fathom.
# ---
# * GSL::CONST::MKSA::KNOT
#
#   The speed of 1 knot.
#
# == Printers Units
# ---
# * GSL::CONST::MKSA::POINT
#
#   The length of 1 printer's point (1/72 inch).
# ---
# * GSL::CONST::MKSA::TEXPOINT
#
#   The length of 1 TeX point (1/72.27 inch).
#
# == Volume
# ---
# * GSL::CONST::MKSA::ACRE
#
#   The area of 1 acre.
# ---
# * GSL::CONST::MKSA::LITER
#
#   The volume of 1 liter.
# ---
# * GSL::CONST::MKSA::US_GALLON
#
#   The volume of 1 US gallon.
# ---
# * GSL::CONST::MKSA::CANADIAN_GALLON
#
#   The volume of 1 Canadian gallon.
# ---
# * GSL::CONST::MKSA::UK_GALLON
#
#   The volume of 1 UK gallon.
# ---
# * GSL::CONST::MKSA::QUART
#
#   The volume of 1 quart.
# ---
# * GSL::CONST::MKSA::PINT
#
#   The volume of 1 pint.
#
# == Mass and Weight
# ---
# * GSL::CONST::MKSA::POUND_MASS
#
#   The mass of 1 pound.
# ---
# * GSL::CONST::MKSA::OUNCE_MASS
#
#   The mass of 1 ounce.
# ---
# * GSL::CONST::MKSA::TON
#
#   The mass of 1 ton.
# ---
# * GSL::CONST::MKSA::METRIC_TON
#
#   The mass of 1 metric ton (1000 kg).
# ---
# * GSL::CONST::MKSA::UK_TON
#
#   The mass of 1 UK ton.
# ---
# * GSL::CONST::MKSA::TROY_OUNCE
#
#   The mass of 1 troy ounce.
# ---
# * GSL::CONST::MKSA::CARAT
#
#   The mass of 1 carat.
# ---
# * GSL::CONST::MKSA::GRAM_FORCE
#
#   The force of 1 gram weight.
# ---
# * GSL::CONST::MKSA::POUND_FORCE
#
#   The force of 1 pound weight.
# ---
# * GSL::CONST::MKSA::KILOPOUND_FORCE
#
#   The force of 1 kilopound weight.
# ---
# * GSL::CONST::MKSA::POUNDAL
#
#   The force of 1 poundal.
#
# == Thermal Energy and Power
# ---
# * GSL::CONST::MKSA::CALORIE
#
#   The energy of 1 calorie.
# ---
# * GSL::CONST::MKSA::BTU
#
#   The energy of 1 British Thermal Unit, btu.
# ---
# * GSL::CONST::MKSA::THERM
#
#   The energy of 1 Therm.
# ---
# * GSL::CONST::MKSA::HORSEPOWER
#
#   The power of 1 horsepower.
#
# == Pressure
# ---
# * GSL::CONST::MKSA::BAR
#
#   The pressure of 1 bar.
# ---
# * GSL::CONST::MKSA::STD_ATMOSPHERE
#
#   The pressure of 1 standard atmosphere.
# ---
# * GSL::CONST::MKSA::TORR
#
#   The pressure of 1 torr.
# ---
# * GSL::CONST::MKSA::METER_OF_MERCURY
#
#   The pressure of 1 meter of mercury.
# ---
# * GSL::CONST::MKSA::INCH_OF_MERCURY
#
#   The pressure of 1 inch of mercury.
# ---
# * GSL::CONST::MKSA::INCH_OF_WATER
#
#   The pressure of 1 inch of water.
# ---
# * GSL::CONST::MKSA::PSI
#
#   The pressure of 1 pound per square inch.
#
# == Viscosity
# ---
# * GSL::CONST::MKSA::POISE
#
#   The dynamic viscosity of 1 poise.
# ---
# * GSL::CONST::MKSA::STOKES
#
#   The kinematic viscosity of 1 stokes.
#
# == Light and Illumination
# ---
# * GSL::CONST::MKSA::STILB
#
#   The luminance of 1 stilb.
# ---
# * GSL::CONST::MKSA::LUMEN
#
#   The luminous flux of 1 lumen.
# ---
# * GSL::CONST::MKSA::LUX
#
#   The illuminance of 1 lux.
# ---
# * GSL::CONST::MKSA::PHOT
#
#   The illuminance of 1 phot.
# ---
# * GSL::CONST::MKSA::FOOTCANDLE
#
#   The illuminance of 1 footcandle.
# ---
# * GSL::CONST::MKSA::LAMBERT
#
#   The luminance of 1 lambert.
# ---
# * GSL::CONST::MKSA::FOOTLAMBERT
#
#   The luminance of 1 footlambert.
#
# == Radioactivity
# ---
# * GSL::CONST::MKSA::CURIE
#
#   The activity of 1 curie.
# ---
# * GSL::CONST::MKSA::ROENTGEN
#
#   The exposure of 1 roentgen.
# ---
# * GSL::CONST::MKSA::RAD
#
#   The absorbed dose of 1 rad.
#
# == Force and Energy
# ---
# * GSL::CONST::MKSA::NEWTON
#
#   The SI unit of force, 1 Newton.
# ---
# * GSL::CONST::MKSA::DYNE
#
#   he force of 1 Dyne = 10^-5 Newton.
# ---
# * GSL::CONST::MKSA::JOULE
#
#   The SI unit of energy, 1 Joule.
# ---
# * GSL::CONST::MKSA::ERG
#
#   The energy 1 erg = 10^-7 Joule.
#
# == Prefixes
# ---
# * GSL::CONST::NUM::YOTTA
#
#   10^24
# ---
# * GSL::CONST::NUM::ZETTA
#
#   10^21
# ---
# * GSL::CONST::NUM::EXA
#
#   10^18
# ---
# * GSL::CONST::NUM::PETA
#
#   10^15
# ---
# * GSL::CONST::NUM::TERA
#
#   10^12
# ---
# * GSL::CONST::NUM::GIGA
#
#   10^9
# ---
# * GSL::CONST::NUM::MEGA
#
#   10^6
# ---
# * GSL::CONST::NUM::KILO
#
#   10^3
# ---
# * GSL::CONST::NUM::MILLI
#
#   10^-3
# ---
# * GSL::CONST::NUM::MICRO
#
#   10^-6
# ---
# * GSL::CONST::NUM::NANO
#
#   10^-9
# ---
# * GSL::CONST::NUM::PICO
#
#   10^-12
# ---
# * GSL::CONST::NUM::FEMTO
#
#   10^-15
# ---
# * GSL::CONST::NUM::ATTO
#
#   10^-18
# ---
# * GSL::CONST::NUM::ZEPTO
#
#   10^-21
# ---
# * GSL::CONST::NUM::YOCTO
#
#   10^-24
#
# == Example
# The following program demonstrates the use of the physical constants in a
# calculation. In this case, the goal is to calculate the range of light-travel
# times from Earth to Mars.
#
#      require("gsl")
#      include GSL::CONST::MKSA
#
#      puts("In MKSA unit")
#
#      c  = SPEED_OF_LIGHT;
#      au = ASTRONOMICAL_UNIT;
#      minutes = MINUTE;
#
#      # distance stored in meters
#      r_earth = 1.00 * au;
#      r_mars  = 1.52 * au;
#
#      t_min = (r_mars - r_earth) / c;
#      t_max = (r_mars + r_earth) / c;
#
#      printf("light travel time from Earth to Mars:\n");
#      printf("c = %e [m/s]\n", c)
#      printf("AU = %e [m]\n", au)
#      printf("minutes = %e [s]\n", minutes)
#      printf("minimum = %.1f minutes\n", t_min / minutes);
#      printf("maximum = %.1f minutes\n\n", t_max / minutes);
#
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#
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#
#
