text: #define _USE_MATH_DEFINES
  #include <iostream>
  #include <cmath>
  #include "../matplotlibcpp.h"
  
  namespace plt = matplotlibcpp;
  
  int main() 
  {
      // Prepare data.
      int n = 5000;
      std::vector<double> x(n), y(n), z(n), w(n,2);
      for(int i=0; i<n; ++i) {
          x.at(i) = i*i;
          y.at(i) = sin(2*M_PI*i/360.0);
          z.at(i) = log(i);
      }
      
      // Set the size of output image = 1200x780 pixels
      plt::figure_size(1200, 780);
  
      // Plot line from given x and y data. Color is selected automatically.
      plt::plot(x, y);
  
      // Plot a red dashed line from given x and y data.
      plt::plot(x, w,"r--");
  
      // Plot a line whose name will show up as "log(x)" in the legend.
      plt::named_plot("log(x)", x, z);
  
      // Set x-axis to interval [0,1000000]
      plt::xlim(0, 1000*1000);
  
      // Add graph title
      plt::title("Sample figure");
  
      // Enable legend.
      plt::legend();
  
      // save figure
      const char* filename = "./basic.png";
      std::cout << "Saving result to " << filename << std::endl;;
      plt::save(filename);
  }
  