#include <cstdio>
#include <cmath>
#include <armadillo>

int main()
{
	printf("Hallo, Welt!\n");

	// Position of a particle                     //    |
	arma::vec Pos = {{0},                         //    | (0,1)
				   {1}};                        //    +---x-->

	// Rotation matrix 
	double phi = -3.1416/2; 
	arma::mat RotM = {{+cos(phi), -sin(phi)},
					{+sin(phi), +cos(phi)}};

	Pos.print("Current position of the particle:");
	std::cout << "Rotating the point " << phi*180/3.1416 << " deg" << std::endl;

	Pos = RotM*Pos;

	Pos.print("New position of the particle:");   //    ^
												//    x (1,0)
												//    | 
	arma::mat Z = arma::eye<arma::mat>(4,4);
	Z.print("Z:");
	printf("Z.n_rows = %d\n", (int)Z.n_rows);
	printf("Z.n_cols = %d\n", (int)Z.n_cols);
	printf("Z.n_elem = %d\n", (int)Z.n_elem);
	//    +------>

	return 0;
}