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CONSTANTS

CONSTANTS

## Purpose

This procedure returns the values of some absolute constants.

Miscellaneous

## Calling Sequence

CONSTANTS, \$
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

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

## Optional Outputs

AU: Astronomical unit (the Earth-Sun distance).
BOLTZMANN: Boltzmann constant.
CELSIUS_KELVIN: The conversion between degress Celsius and Kelvins.
CT_LWATER: Specific heat of liquid water at 0C.
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_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

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

Return the value of pi.
constants, pi=pi

## Modification History

Written by: Daithi A. Stone (stoned@uvic.ca), 2000-06-27.
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).