Name

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CONSTANTS

Purpose

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This procedure returns the values of some absolute constants.

Category

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Miscellaneous

Calling Sequence

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CONSTANTS, $
[ PI=pi, NDEGREE=ndegree, DEGRAD=degrad, NAN=nan, IM=im, $
      DINA=dina, MINA=mina, $
R_EARTH=r_earth, G_EARTH=g_earth, MSLP=mslp, VA_EARTH, $
CELSIUS_KELVIN=celsius_kelvin, $
STEFAN_BOLTZMANN=stefan_boltzmann, $
R_GAS=r_gas ]

Keyword Parameters

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DOUBLE: If set, floating point numbers are returned in double
precision. The default is single precision.

Optional Outputs

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AU: Astronomical unit (the Earth-Sun distance).
AVOGADRO: Avogadro constant.
BOLTZMANN: Boltzmann constant.
CELSIUS_KELVIN: The conversion between degress Celsius and Kelvins.
CT_LWATER: Specific heat of liquid water at 0C.
DEGRAD: Degrees to radians conversion coefficient.
DINA: Number of days in a year.
G_EARTH: Mean gravitational acceleration at Earth's surface.
HF_WATER: Latent heat of fusion of water at 0C.
HIND: The number of hours in a day.
HV_WATER: Latent heat of vaporisation of water at 100C.
IM: The imaginary number i=sqrt(-1).
M_EARTH: Mass of Earth.
MSLP: Mean global sea level pressure on Earth.
MINA: Number of months in a year.
MINH: The number of minutes in an hour.
NAN: Not-a-Number value.
NDEGREE: Number of degrees in a circle.
OMEGA_EARTH: Angular rotation speed of Earth.
PI: pi=3.14...
R_EARTH: Radius of Earth.
R_GAS: Molar gas constant.
RHO_DRYAIR: Density of dry air at 0C and 100kPa.
RHO_LWATER: Density of liquid water at 0C.
SINM: The number of seconds in a minute.
STEFAN_BOLTZMANN: Stefan-Boltzmann constant.

Procedure

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This procedure defines all values. Values are obtained from the
following references.
Serway, R.A. 1992. Physics for Scientist and Engineers with Modern
Physics, 3rd edition, Updated Printing. Saunders College
Publishing, Toronto, Ontario, 1444p.
Weast, R.C., and M.J. Astle, eds. 1980. CRC Handbook of Chemistry
and Physics, 61st edition. CRC Press, Inc., Boca Raton,
Florida.
National Institute of Standards and Technology.
http://physics.nist.gov/PhysRefData/

Example

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Return the value of pi.
constants, pi=pi

Modification History

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  Written by: Daithi A. Stone (stoned@uvic.ca), 2000-06-27.
Modified: DAS, 2000-07-24 (added DEGRAD output keyword).
Modified: DAS, 2001-05-18 (added DOUBLE keyword, and SINM, MINH,
HIND output keywords).
Modified: DAS, 2001-08-13 (added GEARTH, CELSIUS_KELVIN output).
Modified: DAS, 2001-11-22 (added STEFAN_BOLTZMANN output).
Modified: DAS, 2002-08-09 (added AU, AVOGADRO, BOLTZMANN,
CT_LWATER, HF_WATER, HV_WATER, M_EARTH, OMEGA_EARTH,
R_GAS, RHO_DRYAIR, RHO_LWATER output, modified and
referenced CELSIUS_KELVIN, G_EARTH, MSLP, R_EARTH,
STEFAN_BOLTZMANN outputs).