Eigen: Get scalar type from array type is documented?

Question

I want to know if getting the scalar type from the array type by ArrayType::Scalar is documented for the Eigen library.

The following compiles (g++ test.cpp -I<Path to Eigen> -frtti)

#include <Eigen/Eigen>
#include <typeinfo>
#include <iostream>
int main() {
    Eigen::ArrayXf::Scalar i = 0;
    std::cout << typeid(i).name() << "\n";
}

Result (float type as expected):

f

That also works for MatrixXf type.

Answer 1

Yes. It is documented by doxygen, at least for DenseBase. I found it when I searched for "scalar" in https://eigen.tuxfamily.org/dox/

template<typename Derived>
typedef internal::traits<Derived>::Scalar Eigen::DenseBase< Derived >::Scalar

The numeric type of the expression' coefficients, e.g. float, double, int or std::complex, etc.