Function monte_carlo_pi

exprtk_simple_example_17.cpp:45–73

template <typename T>
void monte_carlo_pi()
{
   typedef exprtk::symbol_table<T> symbol_table_t;
   typedef exprtk::expression<T>   expression_t;
   typedef exprtk::parser<T>       parser_t;

   const std::string monte_carlo_pi_program =
      " var samples[2 * 10^8] := [(rnd_01^2 + rnd_01^2) <= 1]; "
      " 4 * sum(samples) / samples[];                          ";

   rnd_01<T> rnd01;

   symbol_table_t symbol_table;
   symbol_table.add_function("rnd_01",rnd01);

   expression_t expression;
   expression.register_symbol_table(symbol_table);

   parser_t parser;
   parser.compile(monte_carlo_pi_program,expression);

   const T approximate_pi = expression.value();

   const T real_pi = T(3.141592653589793238462643383279502); // or close enough...

   printf("pi ~ %20.17f\terror: %20.17f\n",
          approximate_pi,
          std::abs(real_pi - approximate_pi));
}

int main()
{