    //Copyright (C) 2013 Steve Taylor (steve98654@gmail.com), Davis E. King
    //License: Boost Software License.  See LICENSE.txt for full license.
    #ifndef DLIB_NUMERIC_CONSTANTs_H_
    #define DLIB_NUMERIC_CONSTANTs_H_

    namespace dlib
    {

        // pi -- Pi
        const double pi = 3.1415926535897932385;

        // e  -- Euler's Constant
        const double e = 2.7182818284590452354;

        // sqrt_2 -- The square root of 2
        const double sqrt_2 = 1.4142135623730950488;

        // sqrt_3 -- The square root of 3
        const double sqrt_3 = 1.7320508075688772935;

        // log10_2 -- The logarithm base 10 of two
        const double log10_2 = 0.30102999566398119521;

        // light_spd -- The speed of light in vacuum in meters per second
        const double light_spd = 2.99792458e8;

        // newton_G  -- Newton's gravitational constant (in metric units of m^3/(kg*s^2))
        const double newton_G = 6.67384e-11;

        // planck_cst -- Planck's constant (in units of Joules * seconds)
        const double planck_cst = 6.62606957e-34;

        // golden_ratio -- The Golden Ratio
        const double golden_ratio = 1.6180339887498948482;

        // euler_gamma -- The Euler Mascheroni Constant
        const double euler_gamma = 0.5772156649015328606065;

        // catalan -- Catalan's Constant
        const double catalan = 0.91596559417721901505;

        // glaisher -- Glaisher Kinkelin constant
        const double glaisher = 1.2824271291006226369;

        // khinchin -- Khinchin's constant
        const double khinchin = 2.6854520010653064453;

        // apery -- Apery's constant
        const double apery = 1.2020569031595942854;
    }

    #endif //DLIB_NUMERIC_CONSTANTs_H_