exprtk_funcall_benchmark.cpp

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/*
 **************************************************************
 *         C++ Mathematical Expression Toolkit Library        *
 *                                                            *
 * Function Call Benchmark (Custom vs Composite vs Native)    *
 * Author: Arash Partow (1999-2025)                           *
 * URL: https://www.partow.net/programming/exprtk/index.html  *
 *                                                            *
 * Copyright notice:                                          *
 * Free use of the Mathematical Expression Toolkit Library is *
 * permitted under the guidelines and in accordance with the  *
 * most current version of the MIT License.                   *
 * https://www.opensource.org/licenses/MIT                    *
 * SPDX-License-Identifier: MIT                               *
 *                                                            *
 **************************************************************
*/
 
 
#include <cstdio>
#include <string>
 
#include "exprtk.hpp"
 
 
template <typename T>
struct func0 : public exprtk::ifunction<T>
{
   using exprtk::ifunction<T>::operator();
 
   func0()
   : exprtk::ifunction<T>(2)
   {}
 
   inline T operator()(const T& v1, const T& v2)
   {
      return T(1) + std::cos(v1 * v2) / T(3);
   }
};
 
template <typename T>
inline T func1(T v1, T v2)
{
   return T(1) + std::cos(v1 * v2) / T(3);
}
 
template <typename T>
void function_call_benchmark01()
{
   typedef exprtk::symbol_table<T>         symbol_table_t;
   typedef exprtk::expression<T>           expression_t;
   typedef exprtk::parser<T>               parser_t;
   typedef exprtk::function_compositor<T>  compositor_t;
   typedef typename compositor_t::function function_t;
 
   T v1 = T(1);
   T v2 = T(2);
 
   func0<T> f0;
 
   symbol_table_t symbol_table;
 
   symbol_table.add_constants();
 
   symbol_table.add_variable("v1"   , v1           );
   symbol_table.add_variable("v2"   , v2           );
   symbol_table.add_function("func0", f0           );
   symbol_table.add_function("func1", func1<double>);
 
   compositor_t compositor(symbol_table);
 
   compositor.add(
      function_t("func2")
      .var("v1").var("v2")
      .expression(" 1 + cos(v1 * v2) / 3;"));
 
   const std::string program0 = "func0(v1,v2);";
   const std::string program1 = "func1(v1,v2);";
   const std::string program2 = "func2(v1,v2);";
 
   expression_t expression0(symbol_table);
   expression_t expression1(symbol_table);
   expression_t expression2(symbol_table);
 
   parser_t parser;
 
   if (!parser.compile(program0,expression0))
   {
      printf("Error: %s\tExpression: %s\n",
             parser.error().c_str(),
             program0.c_str());
 
      return;
   }
 
   if (!parser.compile(program1,expression1))
   {
      printf("Error: %s\tExpression: %s\n",
             parser.error().c_str(),
             program1.c_str());
 
      return;
   }
 
   if (!parser.compile(program2,expression2))
   {
      printf("Error: %s\tExpression: %s\n",
             parser.error().c_str(),
             program1.c_str());
 
      return;
   }
 
   const std::size_t rounds = 100000000;
 
   {
      T total = T(0);
 
      exprtk::timer timer;
      timer.start();
 
      for (std::size_t r = 0; r < rounds; ++r)
      {
         total += expression0.value();
         std::swap(v1,v2);
      }
 
      timer.stop();
 
      printf("[custom function]  Total time: %8.3fsec\tRate: %15.3f\tTotal:%20.5f\n",
             timer.time(),
             rounds / timer.time(),
             total);
   }
 
   {
      T total = T(0);
 
      exprtk::timer timer;
      timer.start();
 
      for (std::size_t r = 0; r < rounds; ++r)
      {
         total += expression1.value();
         std::swap(v1,v2);
      }
 
      timer.stop();
 
      printf("[free function  ]  Total time: %8.3fsec\tRate: %15.3f\tTotal:%20.5f\n",
             timer.time(),
             rounds / timer.time(),
             total);
   }
 
   {
      T total = T(0);
 
      exprtk::timer timer;
      timer.start();
 
      for (std::size_t r = 0; r < rounds; ++r)
      {
         total += expression2.value();
         std::swap(v1,v2);
      }
 
      timer.stop();
 
      printf("[compositor     ]  Total time: %8.3fsec\tRate: %15.3f\tTotal:%20.5f\n",
             timer.time(),
             rounds / timer.time(),
             total);
   }
 
   {
      T total = T(0);
 
      exprtk::timer timer;
      timer.start();
 
      for (std::size_t r = 0; r < rounds; ++r)
      {
         total += func1<T>(v1,v2);
         std::swap(v1,v2);
      }
 
      timer.stop();
 
      printf("[native         ]  Total time: %8.3fsec\tRate: %15.3f\tTotal:%20.5f\n",
             timer.time(),
             rounds / timer.time(),
             total);
   }
}
 
int main()
{
   function_call_benchmark01<double>();
   return 0;
}