.. _program_listing_file_dx2_utils.cxx:

Program Listing for File utils.cxx
==================================

|exhale_lsh| :ref:`Return to documentation for file <file_dx2_utils.cxx>` (``dx2/utils.cxx``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   #include "dx2/utils.hpp"
   #include <Eigen/Dense>
   #include <iomanip>
   #include <math.h>
   #include <random>
   #include <sstream>
   
   using Eigen::Vector3d;
   
   double angle_between_vectors_degrees(Vector3d v1, Vector3d v2) {
     double l1 = v1.norm();
     double l2 = v2.norm();
     double dot = v1.dot(v2);
     double normdot = dot / (l1 * l2);
     if (std::abs(normdot - 1.0) < 1E-6) {
       return 0.0;
     }
     if (std::abs(normdot + 1.0) < 1E-6) {
       return 180.0;
     }
     double angle = std::acos(normdot) * 180.0 / M_PI;
     return angle;
   }
   
   std::string ersatz_uuid4() {
     // Generate 16 random bytes
     std::array<unsigned char, 16> bytes;
     std::random_device rd;
     std::uniform_int_distribution<int> dist(0, 255);
     for (auto &b : bytes) {
       b = static_cast<unsigned char>(dist(rd));
     }
   
     // Convert bytes to a single 128-bit hex string (little endian)
     std::ostringstream oss;
     for (auto it = bytes.rbegin(); it != bytes.rend(); ++it) {
       oss << std::hex << std::setw(2) << std::setfill('0')
           << static_cast<int>(*it);
     }
     std::string hex = oss.str();
   
     // Format as UUID: 8-4-4-4-12
     std::ostringstream uuid;
     uuid << hex.substr(0, 8) << "-" << hex.substr(8, 4) << "-"
          << hex.substr(12, 4) << "-" << hex.substr(16, 4) << "-"
          << hex.substr(20, 12);
   
     return uuid.str();
   }