/usr/include/feel/feelpoly/ is in libfeel++-dev 1:0.99.0-final.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/feel/feelpoly/basis.hpp
/usr/include/feel/feelpoly/boundadapted.hpp
/usr/include/feel/feelpoly/boundaryadaptedpolynomialset.hpp
/usr/include/feel/feelpoly/constrainedpolynomialset.hpp
/usr/include/feel/feelpoly/context.hpp
/usr/include/feel/feelpoly/continuity.hpp
/usr/include/feel/feelpoly/crouzeixraviart.hpp
/usr/include/feel/feelpoly/discontinuous.cpp
/usr/include/feel/feelpoly/discontinuous.hpp
/usr/include/feel/feelpoly/discontinuousinterfaces.hpp
/usr/include/feel/feelpoly/dualbasis.hpp
/usr/include/feel/feelpoly/dubiner.hpp
/usr/include/feel/feelpoly/electrostatic.hpp
/usr/include/feel/feelpoly/equispaced.hpp
/usr/include/feel/feelpoly/expansions.hpp
/usr/include/feel/feelpoly/expansiontypes.hpp
/usr/include/feel/feelpoly/fe.hpp
/usr/include/feel/feelpoly/fekete.hpp
/usr/include/feel/feelpoly/functional.hpp
/usr/include/feel/feelpoly/functionals.hpp
/usr/include/feel/feelpoly/functionals2.hpp
/usr/include/feel/feelpoly/functionalset.hpp
/usr/include/feel/feelpoly/gauss.hpp
/usr/include/feel/feelpoly/gausslobatto.hpp
/usr/include/feel/feelpoly/geomap.cpp
/usr/include/feel/feelpoly/geomap.hpp
/usr/include/feel/feelpoly/geomapinv.hpp
/usr/include/feel/feelpoly/hcurlpolynomialset.hpp
/usr/include/feel/feelpoly/hdivpolynomialset.hpp
/usr/include/feel/feelpoly/hermite.hpp
/usr/include/feel/feelpoly/im.hpp
/usr/include/feel/feelpoly/imexact.hpp
/usr/include/feel/feelpoly/imsimplex.hpp
/usr/include/feel/feelpoly/imsimplex2.hpp
/usr/include/feel/feelpoly/isp0continuous.hpp
/usr/include/feel/feelpoly/jacobi.hpp
/usr/include/feel/feelpoly/lagrange.hpp
/usr/include/feel/feelpoly/lebesgue.hpp
/usr/include/feel/feelpoly/legendre.hpp
/usr/include/feel/feelpoly/mapped.hpp
/usr/include/feel/feelpoly/moment.hpp
/usr/include/feel/feelpoly/mortar.hpp
/usr/include/feel/feelpoly/nedelec.hpp
/usr/include/feel/feelpoly/operations.hpp
/usr/include/feel/feelpoly/orthogonalpolynomialset.hpp
/usr/include/feel/feelpoly/orthonormalpolynomialset.hpp
/usr/include/feel/feelpoly/parameter.hpp
/usr/include/feel/feelpoly/pointsetinterpolation.hpp
/usr/include/feel/feelpoly/policy.hpp
/usr/include/feel/feelpoly/polynomial.hpp
/usr/include/feel/feelpoly/polynomialset.hpp
/usr/include/feel/feelpoly/polynomialset_impl.hpp
/usr/include/feel/feelpoly/principal.hpp
/usr/include/feel/feelpoly/quadmapped.hpp
/usr/include/feel/feelpoly/quadpoint.hpp
/usr/include/feel/feelpoly/raviartthomas.hpp
/usr/include/feel/feelpoly/tensorisedboundadapted.hpp
/usr/include/feel/feelpoly/test_equispaced.cpp
/usr/include/feel/feelpoly/warpblend.hpp