Modelica.Constants

Information

This package provides often needed constants from mathematics, machine dependent constants and constants from nature. The latter constants (name, value, description) are from the following source:

Peter J. Mohr and Barry N. Taylor (1999):

CODATA Recommended Values of the Fundamental Physical Constants: 1998. Journal of Physical and Chemical Reference Data, Vol. 28, No. 6, 1999 and Reviews of Modern Physics, Vol. 72, No. 2, 2000. See also http://physics.nist.gov/cuu/Constants/

Main Author:

Martin Otter
Deutsches Zentrum fuer Luft und Raumfahrt e.V. (DLR)
Oberpfaffenhofen
Postfach 1116
D-82230 Wessling
email: Martin.Otter@dlr.de

Release Notes:

• Dec. 9, 1999 by Martin Otter:
  Constants updated according to 1998 CODATA values. Using names, values and description text from this source. Included magnetic and electric constant.
• Sept. 18, 1999 by Martin Otter:
  Constants EPS, INF, SMALL introduced.
• Nov 15, 1997 by Martin Otter:
  Realized.

Copyright (C) 1999-2000, Modelica Association and DLR.

The Modelica package is free software; it can be redistributed and/or modified under the terms of the Modelica license, see the license conditions and the accompanying disclaimer in the documentation of package Modelica in file "Modelica/package.mo".

Types and constants

  // Mathematical constants
  // (the definition is a temporary fix since not adapted to the
  // machine where the Modelica translator is running)
  constant Real e=Modelica.Math.exp(1.0);
  constant Real pi=2*Modelica.Math.asin(1.0);
  // 3.14159265358979;
  
  // Machine dependent constants
  // (the definition is a temporary fix since not adapted to the
  // machine where the Modelica translator is running)
  constant Real eps=1.e-15 "Biggest number such that 1.0 + EPS = 1.0";
  constant Real small=1.e-60 
    "Smallest number such that small and -small are representable on the machine"
    ;
  constant Real inf=1.e+60 
    "Biggest Real number such that inf and -inf are representable on the machine"
    ;
  constant Integer Integer_inf=2147483647 
    "Biggest Integer number such that Integer_inf and -Integer_inf are representable on the machine"
    ;
  
  // Constants of nature 
  // (name, value, description from http://physics.nist.gov/cuu/Constants/)
  constant Modelica.SIunits.Velocity c=299792458 "Speed of light in vacuum";
  constant Modelica.SIunits.Acceleration g_n=9.80665 
    "Standard acceleration of gravity on earth";
  constant Real G(final unit="m3/(kg.s2)") = 6.673e-11 
    "Newtonian constant of gravitation";
  constant Real h(final unit="J.s") = 6.62606876e-34 "Planck constant";
  constant Real k(final unit="J/K") = 1.3806503e-23 "Boltzmann constant";
  constant Real R(final unit="J/(mol.K)") = 8.314472 "Molar gas constant";
  constant Real sigma(final unit="W/(m2.K4)") = 5.670400e-8 
    "Stefan-Boltzmann constant";
  constant Real N_A(final unit="1/mol") = 6.02214199e23 "Avogadro constant";
  constant Real mue_0(final unit="N/A2") = 4*pi*1.e-7 "Magnetic constant";
  constant Real epsilon_0(final unit="F/m") = 1/(mue_0*c*c) 
    "Electric constant";
  constant Modelica.SIunits.CelsiusTemperature T_zero=-273.15 
    "Absolute zero temperature";
  
  // For compatibility with previous versions (do not use in new models)
  constant Real E=e;
  constant Real PI=pi;
  constant Real EPS=eps;
  constant Real SMALL=small;
  constant Real INF=inf;
  constant Real INTEGER_INF=Integer_inf;
  constant Real C=c;
  constant Real H=h;
  constant Real K=k;
  constant Real R0=R;
  constant Real SIGMA=sigma;
  constant Real G_EARTH=g_n;
  constant Real T_ZERO=T_zero;