init_glob := proc()
    global c_v, h_v, me_v;
    c_v := 2.99792458e8;      # speed of light in meters/sec
    h_v := 6.62606876e-34;    # Plank's constant in kg meters^2/sec
    me_v := 9.10938188e-31;   # mass of electron in kg
end;