/usr/include/ql/math/optimization/ is in libquantlib0-dev 1.7.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ql/math/optimization/all.hpp
/usr/include/ql/math/optimization/armijo.hpp
/usr/include/ql/math/optimization/bfgs.hpp
/usr/include/ql/math/optimization/conjugategradient.hpp
/usr/include/ql/math/optimization/constraint.hpp
/usr/include/ql/math/optimization/costfunction.hpp
/usr/include/ql/math/optimization/differentialevolution.hpp
/usr/include/ql/math/optimization/endcriteria.hpp
/usr/include/ql/math/optimization/goldstein.hpp
/usr/include/ql/math/optimization/leastsquare.hpp
/usr/include/ql/math/optimization/levenbergmarquardt.hpp
/usr/include/ql/math/optimization/linesearch.hpp
/usr/include/ql/math/optimization/linesearchbasedmethod.hpp
/usr/include/ql/math/optimization/lmdif.hpp
/usr/include/ql/math/optimization/method.hpp
/usr/include/ql/math/optimization/problem.hpp
/usr/include/ql/math/optimization/projectedconstraint.hpp
/usr/include/ql/math/optimization/projectedcostfunction.hpp
/usr/include/ql/math/optimization/projection.hpp
/usr/include/ql/math/optimization/simplex.hpp
/usr/include/ql/math/optimization/simulatedannealing.hpp
/usr/include/ql/math/optimization/spherecylinder.hpp
/usr/include/ql/math/optimization/steepestdescent.hpp