/usr/include/mlpack/core/optimizers/ is in libmlpack-dev 1.0.10-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/mlpack/core/optimizers/aug_lagrangian/
/usr/include/mlpack/core/optimizers/aug_lagrangian/aug_lagrangian.hpp
/usr/include/mlpack/core/optimizers/aug_lagrangian/aug_lagrangian_function.hpp
/usr/include/mlpack/core/optimizers/aug_lagrangian/aug_lagrangian_function_impl.hpp
/usr/include/mlpack/core/optimizers/aug_lagrangian/aug_lagrangian_impl.hpp
/usr/include/mlpack/core/optimizers/aug_lagrangian/aug_lagrangian_test_functions.hpp
/usr/include/mlpack/core/optimizers/lbfgs/
/usr/include/mlpack/core/optimizers/lbfgs/lbfgs.hpp
/usr/include/mlpack/core/optimizers/lbfgs/lbfgs_impl.hpp
/usr/include/mlpack/core/optimizers/lbfgs/test_functions.hpp
/usr/include/mlpack/core/optimizers/lrsdp/
/usr/include/mlpack/core/optimizers/lrsdp/lrsdp.hpp
/usr/include/mlpack/core/optimizers/lrsdp/lrsdp_function.hpp
/usr/include/mlpack/core/optimizers/sa/
/usr/include/mlpack/core/optimizers/sa/exponential_schedule.hpp
/usr/include/mlpack/core/optimizers/sa/sa.hpp
/usr/include/mlpack/core/optimizers/sa/sa_impl.hpp
/usr/include/mlpack/core/optimizers/sgd/
/usr/include/mlpack/core/optimizers/sgd/sgd.hpp
/usr/include/mlpack/core/optimizers/sgd/sgd_impl.hpp
/usr/include/mlpack/core/optimizers/sgd/test_function.hpp