text: #include <cmath>
  #include <matplot/matplot.h>
  
  int main() {
      using namespace matplot;
      std::vector<double> x = linspace(-pi, pi, 40);
      std::vector<double> z = transform(x, [](double x) { return cos(x); });
  
      stem3(z, "filled");
  
      wait();
      return 0;
  }