Does anyone know anyway to use the Eigen API with standard C++. So, I need to create a algorithm library, which will be called by standard C++. For example, I want to use Cholesky, but I would like to pass an array of std::complex or somehow quickly convert that. The conversion idea does not seem good to me as that will take time.

Thanks,

Could you be more specific? Anyway, I guess that what you're looking for is Eigen::Map, see: http://eigen.tuxfamily.org/dox-devel/gr ... Class.html

Yes, maybe that map is OK. I will check it out. Basically I have my data as the std::complex type and I would like to pass this into a Eigen function.