Power.hpp

#ifndef FAIF_UTILS_POWER
#define FAIF_UTILS_POWER

namespace faif {

    /** the template metaprogramming for calculating power of double,
        based on sqare and multiply method, i.e. if n = 2^m (n is m-th power of 2),
        x^n = (...((x^2)^2)...)^2 (m-times)
    */
    template <unsigned n> double int_power(double x) {
        return int_power<2>( int_power<n/2>(x) )*int_power<n%2>(x);
    }

    /** the specialisation for power = 2 */
    template <> double int_power<2>(double x) {
        return x*x;
    }

    /** the specialisation for power = 1 */
    template <> double int_power<1>(double x) {
        return x;
    }

    /** the template specialisation for power = 0 */
    template <> double int_power<0>(double) {
        return 1.0;
    }
}


#endif