% Constants.m
%   This program loads many common constants used in 
%   different kinds of scientific work.  These constants 
%   are the CODATA Internationally recommended values as 
%   of 1998.  
%
% USE:  
%   After using the command "run constants" to load all the 
%   constants into the workspace, type "desc" to see a list
%   and description of all available constants, or "unit" 
%   to see a list of their units.  To use a constant, simply 
%   type the name of the constant as it appears in the list.
%   Type "edit constants" to add your own to the list.
%
% Example:
%   run constants;
%   c               % returns "c = 299792458"
%   desc.c          % returns "Speed of light in free space"
%   unit.c          % returns "meter / second"
%
% NOTE: many more constants are available at:
%     http://physics.nist.gov/cuu/Constants/index.html
%
% Last edit by Colin Joye, 8/9/03

% speed of light
c      = 2.99792458e8;
desc.c = 'Speed of light in free space';
unit.c = 'meter / second';

% permittivity of free space
eps0      = 8.854187817e-12;
desc.eps0 = 'Permittivity of free space';
unit.eps0 = 'Farads / meter';

% permeability of free space
mu0      = pi*4e-7;
desc.mu0 = 'Permeability of free space';
unit.mu0 = 'Henries / meter';

% impedance of free space
eta0      = sqrt(mu0 / eps0);
desc.eta0 = 'Characteristic impedance of free space';
unit.eta0 = 'Ohms';

% Plank's constant
h      = 6.62606876e-34;
desc.h = 'Plank''s constant "h" ';
unit.h = 'Joule * seconds';

% Plank's constant divided by 2pi
hbar      = h/2/pi;
desc.hbar = 'h_bar, Plank''s constant divided by 2pi';
unit.hbar = 'Joule * seconds';

% Elementary charge
e      = 1.602176462e-19;
desc.e = 'Elementary unit of charge';
unit.e = 'Coulombs';

% Classical electron radius
re      = 2.817940285e-15;
desc.re = 'Classical electron radius';
unit.re = 'meters';

% Bohr radius
a0      = 0.5291772083e-10;
desc.a0 = 'Bohr radius';
unit.a0 = 'meters';

% mass of an electron
me      = 9.10938188e-31;
desc.me = 'Electron mass';
unit.me = 'kilograms';

% mass of an electron in MeV
me_MeV      = 0.510998902;
desc.me_MeV = 'Electron mass in MeV';
unit.me_MeV = 'MeV (mega-electronvolts)';

% mass of a proton
mp      = 1.67262158e-27;
desc.mp = 'Proton mass';
unit.mp = 'kilograms';

% electron gyromagnetic ratio
gamma_e      = 1.760859794e11;
desc.gamma_e = 'Electron Gyromagnetic ratio';
unit.gamma_e = 'Tesla^-1 * second^-1';

% Proton gyromagnetic ratio
gamma_p      = 2.67522212e8;
desc.gamma_p = 'Proton Gyromagnetic ratio';
unit.gamma_p = 'Tesla^-1 * second^-1';

% Boltzmann constant
kB      = 1.3806503e-23;
desc.kB = 'Boltzmann''s constant';
unit.kB = 'Joules / Kelvin';

% Avogadro's number
NA      = 6.02214199e23;
desc.NA = 'Avogadro''s number';
unit.NA = 'mol^-1';

% Gravity
gn      = 9.80665;
desc.gn = 'Standard gravitational acceleration';
unit.gn = 'meters / second^2';

% electron volt
eV      = 1.602176462e-19;
desc.eV = 'Electron volt';
unit.eV = 'Joules';

% Rydberg constant
R_inf      = 10973731.568549;
desc.R_inf = 'Rydberg constant';
unit.R_inf = 'meter^-1';

% Alfven Current
Ialfven      = eps0*me/e*c^3;
desc.Ialfven = 'Alfven current';
unit.Ialfven = 'Amps';



% ------- End Constants.m --------------