eigen/unsupported/doc/examples/MatrixPower.cpp

#include <unsupported/Eigen/MatrixFunctions>
#include <iostream>

using namespace Eigen;

int main() {
  const double pi = std::acos(-1.0);
  Matrix3d A;
  A << cos(1), -sin(1), 0, sin(1), cos(1), 0, 0, 0, 1;
  std::cout << "The matrix A is:\n"
            << A
            << "\n\n"
               "The matrix power A^(pi/4) is:\n"
            << A.pow(pi / 4) << std::endl;
  return 0;
}