/usr/include/ql/experimental/finitedifferences/ is in libquantlib0-dev 1.1-2build1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ql/experimental/finitedifferences/all.hpp
/usr/include/ql/experimental/finitedifferences/bicgstab.hpp
/usr/include/ql/experimental/finitedifferences/concentrating1dmesher.hpp
/usr/include/ql/experimental/finitedifferences/craigsneydscheme.hpp
/usr/include/ql/experimental/finitedifferences/dividendbarrieroption.hpp
/usr/include/ql/experimental/finitedifferences/douglasscheme.hpp
/usr/include/ql/experimental/finitedifferences/expliciteulerscheme.hpp
/usr/include/ql/experimental/finitedifferences/fd2dblackscholesvanillaengine.hpp
/usr/include/ql/experimental/finitedifferences/fdbatesvanillaengine.hpp
/usr/include/ql/experimental/finitedifferences/fdblackscholesasianengine.hpp
/usr/include/ql/experimental/finitedifferences/fdblackscholesbarrierengine.hpp
/usr/include/ql/experimental/finitedifferences/fdblackscholesrebateengine.hpp
/usr/include/ql/experimental/finitedifferences/fdblackscholesvanillaengine.hpp
/usr/include/ql/experimental/finitedifferences/fdhestonbarrierengine.hpp
/usr/include/ql/experimental/finitedifferences/fdhestonhullwhitevanillaengine.hpp
/usr/include/ql/experimental/finitedifferences/fdhestonrebateengine.hpp
/usr/include/ql/experimental/finitedifferences/fdhestonvanillaengine.hpp
/usr/include/ql/experimental/finitedifferences/fdm1dmesher.hpp
/usr/include/ql/experimental/finitedifferences/fdm2dblackscholesop.hpp
/usr/include/ql/experimental/finitedifferences/fdm2dblackscholessolver.hpp
/usr/include/ql/experimental/finitedifferences/fdmamericanstepcondition.hpp
/usr/include/ql/experimental/finitedifferences/fdmarithmeticaveragecondition.hpp
/usr/include/ql/experimental/finitedifferences/fdmbackwardsolver.hpp
/usr/include/ql/experimental/finitedifferences/fdmbatesop.hpp
/usr/include/ql/experimental/finitedifferences/fdmbatessolver.hpp
/usr/include/ql/experimental/finitedifferences/fdmbermudanstepcondition.hpp
/usr/include/ql/experimental/finitedifferences/fdmblackscholesmesher.hpp
/usr/include/ql/experimental/finitedifferences/fdmblackscholesmultistrikemesher.hpp
/usr/include/ql/experimental/finitedifferences/fdmblackscholesop.hpp
/usr/include/ql/experimental/finitedifferences/fdmblackscholessolver.hpp
/usr/include/ql/experimental/finitedifferences/fdmdirichletboundary.hpp
/usr/include/ql/experimental/finitedifferences/fdmdividendhandler.hpp
/usr/include/ql/experimental/finitedifferences/fdmhestonhullwhiteop.hpp
/usr/include/ql/experimental/finitedifferences/fdmhestonhullwhitesolver.hpp
/usr/include/ql/experimental/finitedifferences/fdmhestonlikesolverfactory.hpp
/usr/include/ql/experimental/finitedifferences/fdmhestonop.hpp
/usr/include/ql/experimental/finitedifferences/fdmhestonsolver.hpp
/usr/include/ql/experimental/finitedifferences/fdmhestonvariancemesher.hpp
/usr/include/ql/experimental/finitedifferences/fdmhullwhitemesher.hpp
/usr/include/ql/experimental/finitedifferences/fdminnervaluecalculator.hpp
/usr/include/ql/experimental/finitedifferences/fdmlinearop.hpp
/usr/include/ql/experimental/finitedifferences/fdmlinearopcomposite.hpp
/usr/include/ql/experimental/finitedifferences/fdmlinearopiterator.hpp
/usr/include/ql/experimental/finitedifferences/fdmlinearoplayout.hpp
/usr/include/ql/experimental/finitedifferences/fdmmesher.hpp
/usr/include/ql/experimental/finitedifferences/fdmmeshercomposite.hpp
/usr/include/ql/experimental/finitedifferences/fdmquantohelper.hpp
/usr/include/ql/experimental/finitedifferences/fdmsimple2dbssolver.hpp
/usr/include/ql/experimental/finitedifferences/fdmsnapshotcondition.hpp
/usr/include/ql/experimental/finitedifferences/fdmstepconditioncomposite.hpp
/usr/include/ql/experimental/finitedifferences/firstderivativeop.hpp
/usr/include/ql/experimental/finitedifferences/hundsdorferscheme.hpp
/usr/include/ql/experimental/finitedifferences/impliciteulerscheme.hpp
/usr/include/ql/experimental/finitedifferences/modifiedcraigsneydscheme.hpp
/usr/include/ql/experimental/finitedifferences/ninepointlinearop.hpp
/usr/include/ql/experimental/finitedifferences/secondderivativeop.hpp
/usr/include/ql/experimental/finitedifferences/secondordermixedderivativeop.hpp
/usr/include/ql/experimental/finitedifferences/sparseilupreconditioner.hpp
/usr/include/ql/experimental/finitedifferences/triplebandlinearop.hpp
/usr/include/ql/experimental/finitedifferences/uniform1dmesher.hpp
/usr/include/ql/experimental/finitedifferences/uniformgridmesher.hpp