eigen/doc/examples/Tutorial_ArrayClass_addition.cpp

#include <Eigen/Dense>
#include <iostream>

int main() {
  Eigen::ArrayXXf a(3, 3);
  Eigen::ArrayXXf b(3, 3);
  a << 1, 2, 3, 4, 5, 6, 7, 8, 9;
  b << 1, 2, 3, 1, 2, 3, 1, 2, 3;

  // Adding two arrays
  std::cout << "a + b = " << std::endl << a + b << std::endl << std::endl;

  // Subtracting a scalar from an array
  std::cout << "a - 2 = " << std::endl << a - 2 << std::endl;
}