ouput Eigen matrices in matlab / octave compatible format

octout.cpp

/*
 * this stuff can go in a header to make std::complex<> available
 */
/* compile:
   clang++ -std=c++11 test3.cpp -I eigen/  -DEIGEN_TOO
*/
typedef double real_t;

#include <iostream>
#include <complex>

template <typename Tp>
struct cxwrap : public std::complex<Tp> {
  typedef std::complex<Tp> base_t;
  using base_t::base_t;
  cxwrap<Tp>(const base_t & cx) : base_t(cx) {}
  operator base_t() { return *this; }
  using base_t::operator+=;
  using base_t::operator-=;
  using base_t::operator*=;
  using base_t::operator/=;
  using base_t::operator=;
  using base_t::real;
  using base_t::imag;

  template <class T, class CharT, class Traits>
  friend std::basic_ostream<CharT, Traits>&
  operator<<(std::basic_ostream<CharT, Traits>& os,
             const cxwrap<T>& x);
};

#ifdef EIGEN_TOO
#include <Eigen/Dense>
namespace Eigen {
template<typename _Real> struct NumTraits<cxwrap<_Real> >
: NumTraits<std::complex<_Real> > {};
}
typedef cxwrap<real_t> complext;
#endif

/*
 * below here can go in a .cpp file
 */

template <class T, class CharT, class Traits>
std::basic_ostream<CharT, Traits>&
operator<<(std::basic_ostream<CharT, Traits>& o,
           const cxwrap<T>& x)
{
  std::basic_ostringstream<CharT, Traits> s;
  s.flags(o.flags());
  s.imbue(o.getloc());
  s.precision(o.precision());
  s << x.real() << std::showpos << x.imag() << "i";
  return o << s.str();
}

#include <Eigen/Dense>

//using namespace std::literals::complex_literals;

int main(int argc, char * argv[])
{
  Eigen::Matrix<complext, 3,3> x;
  Eigen::IOFormat NormalFmt;
  Eigen::IOFormat OctaveFmt(Eigen::StreamPrecision, 0, ", ", ";\n", "", "", "[", "]");
  complext y = std::complex<double>(1,2);

  //y = 1.0 + 1i;
  //srand((unsigned int) time(0));
  x.setRandom();
  std::cout << sinh(y) << "\n";
  std::cout << "------------------------\n";
  std::cout << x << "\n";
  std::cout << "------------------------\n";
  std::cout << (x+x).format(NormalFmt) << "\n";
  std::cout << "------------------------\n";
  std::cout << (x*x).format(OctaveFmt) << "\n";
  std::cout << "------------------------\n";
}