\(\newcommand{\W}[1]{ \; #1 \; }\) \(\newcommand{\R}[1]{ {\rm #1} }\) \(\newcommand{\B}[1]{ {\bf #1} }\) \(\newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} }\) \(\newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} }\) \(\newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} }\) \(\newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }\)

speed_test.cpp

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speed_test: Example and test

# include <cppad/utility/speed_test.hpp>
# include <cppad/utility/vector.hpp>

namespace { // empty namespace
   using CppAD::vector;
   vector<double> a, b, c;
   void test(size_t size, size_t repeat)
   {  // setup
      a.resize(size);
      b.resize(size);
      c.resize(size);
      size_t i  = size;;
      while(i)
      {  --i;
         a[i] = double(i);
         b[i] = double(2 * i);
         c[i] = 0.0;
      }
      // operations we are timing
      while(repeat--)
      {  i = size;;
         while(i)
         {  --i;
            c[i] += std::sqrt(a[i] * a[i] + b[i] * b[i]);
         }
      }
   }
}
bool speed_test(void)
{  bool ok = true;

   // size of the test cases
   vector<size_t> size_vec(2);
   size_vec[0] = 40;
   size_vec[1] = 80;

   // minimum amount of time to run test
   double time_min = 0.5;

   // run the test cases
   vector<size_t> rate_vec(2);
   rate_vec = CppAD::speed_test(test, size_vec, time_min);

   // time per repeat loop (note counting setup or teardown)
   double time_0 = 1. / double(rate_vec[0]);
   double time_1 = 1. / double(rate_vec[1]);

   // for this case, time should be linear w.r.t size
   double check    = double(size_vec[1]) * time_0 / double(size_vec[0]);
   double rel_diff = (check - time_1) / time_1;
   ok             &= (std::fabs(rel_diff) <= .1);
   if( ! ok )
      std::cout << std::endl << "rel_diff = " << rel_diff << std::endl;

   a.clear();
   b.clear();
   c.clear();
   return ok;
}