Minkowski distance function

minkowski_distance.cc

// All rights reserved,
// Derrick Pallas
// License: zlib
 
#include <cmath>
#include <cstdlib>
#include <limits>
#include <vector>

template <typename fp_type>
fp_type minkowski_distance(const fp_type & p, const std::vector<fp_type> & ds) {
    // ds contains d[i] = v[i] - w[i] for two vectors v and w
    fp_type ex = 0.0;
    fp_type min_d = std::numeric_limits<fp_type>::infinity();
    fp_type max_d = -std::numeric_limits<fp_type>::infinity();
    for (int i = 0 ; i < ds.size() ; ++i) {
        fp_type d = std::fabs(ds[i]);
        ex += std::pow(d, p);
        min_d = std::min(min_d, d);
        max_d = std::max(max_d, d);
    }

    return std::isnan(ex) ? ex
         : !std::isnormal(ex) && std::signbit(p) ? min_d
         : !std::isnormal(ex) && !std::signbit(p) ? max_d
         : std::pow(ex, 1.0/p);
}

//

p may not be the same type as ds

nice code