Eigen is a C++ template library for linear algebra: matrices, vectors, numerical solvers, and related algorithms.
To use it, add
${CK_FLAG_PREFIX_INCLUDE}${CK_ENV_LIB_EIGEN}
to the list of your compiler options.
Or add CK_ENV_LIB_EIGEN to compiler_add_include_as_env_from_deps array:
"compiler_add_include_as_env_from_deps": [
"CK_ENV_LIB_EIGEN"
]