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  1. #include <cmath>
  2. #include <iostream>
  3. #include <iomanip>
  4. #include <chrono>
  5.  
  6. using namespace std;
  7.  
  8. class muTimer
  9. {
  10.     using Clock = std::chrono::high_resolution_clock;
  11.     bool active = false;
  12.     Clock::duration   duration_;
  13.     Clock::time_point start_ = Clock::now(), stop_ = Clock::now();
  14.  
  15.     muTimer(const muTimer&)             = delete;
  16.     muTimer& operator=(const muTimer&)  = delete;
  17. public:
  18.     using ns       = std::chrono::nanoseconds;
  19.     using mks      = std::chrono::microseconds;
  20.     using ms       = std::chrono::milliseconds;
  21.     muTimer() { reset(); start(); }
  22.     ~muTimer() = default;
  23.     muTimer& reset()
  24.     {
  25.         duration_ = std::chrono::nanoseconds(0);
  26.         active    = false;
  27.         return *this;
  28.     }
  29.     muTimer& start()
  30.     {
  31.         if (!active)
  32.         {
  33.             start_ = Clock::now();
  34.             active = true;
  35.         }
  36.         return *this;
  37.     }
  38.     muTimer& stop()
  39.     {
  40.         if (active)
  41.         {
  42.             stop_      = Clock::now();
  43.             duration_ += stop_ - start_;
  44.             active     = false;
  45.         }
  46.         return *this;
  47.     }
  48.     template<typename T = mks>
  49.         unsigned long long duration()
  50.     {
  51.         return static_cast<unsigned long long>
  52.             (std::chrono::duration_cast<T>(stop_-start_).count());
  53.     }
  54. };
  55.  
  56.  
  57. double expnt(double x, double eps)
  58. {
  59.     double sum = 1.0, term = 1.0;
  60.     for(int n = 1; abs(term) > eps; ++n) sum += term *= x/n;
  61.     return sum;
  62. }
  63.  
  64. double fct(int nmb)
  65. {
  66.     double f = 1;
  67.     for(int i = 2; i <= nmb; ++i) f *= i;
  68.     return f;
  69. }
  70.  
  71. double Expnt(double x, double eps)
  72. {
  73.     double res = 1;
  74.     for(int k = 1; (abs(pow(x,k)/fct(k))) > eps; k++)
  75.         res += pow(x,k)/fct(k);
  76.     return res;
  77. }
  78.  
  79. int main()
  80. {
  81.     {
  82.         muTimer mt;
  83.         double sum = 0;
  84.         for(double x = 0; x < 20; x += 0.001)
  85.             sum += expnt(x,1e-14);
  86.         mt.stop();
  87.         cout << sum << "  for " << mt.duration<>() << " mks\n";
  88.     }
  89.     {
  90.         muTimer mt;
  91.         double sum = 0;
  92.         for(double x = 0; x < 20; x += 0.001)
  93.             sum += Expnt(x,1e-14);
  94.         mt.stop();
  95.         cout << sum << "  for " << mt.duration<>() << " mks\n";
  96.     }
  97. }
  98.  
Success #stdin #stdout 0.12s 4388KB
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stdin
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Standard input is empty
stdout
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4.84923e+11  for 3527 mks
4.84923e+11  for 117301 mks
https://ideone.com/rAxUGm
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
public

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