.. _program_listing_file_examples_test_rk4_only.cpp:

Program Listing for File test_rk4_only.cpp
==========================================

|exhale_lsh| :ref:`Return to documentation for file <file_examples_test_rk4_only.cpp>` (``examples/test_rk4_only.cpp``)

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

.. code-block:: cpp

   #include <diffeq.hpp>
   #include <iostream>
   #include <vector>
   
   void exponential_decay(double t, const std::vector<double>& y, std::vector<double>& dydt) {
       dydt[0] = -y[0];
   }
   
   int main() {
       std::cout << "Testing RK4 only..." << std::endl;
       
       try {
           std::vector<double> y = {1.0};
           auto integrator = diffeq::RK4Integrator<std::vector<double>>(exponential_decay);
           integrator.set_time(0.0);
           integrator.integrate(y, 0.1, 1.0);
           std::cout << "RK4 result: " << y[0] << " (expected: " << std::exp(-1.0) << ")" << std::endl;
               std::cout << "[PASS] RK4 test passed!" << std::endl;
   } catch (const std::exception& e) {
       std::cout << "[FAIL] RK4 test failed: " << e.what() << std::endl;
           return 1;
       }
       
       return 0;
   }