/usr/include/ql/math/matrixutilities/ is in libquantlib0-dev 1.7.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ql/math/matrixutilities/all.hpp
/usr/include/ql/math/matrixutilities/basisincompleteordered.hpp
/usr/include/ql/math/matrixutilities/bicgstab.hpp
/usr/include/ql/math/matrixutilities/choleskydecomposition.hpp
/usr/include/ql/math/matrixutilities/factorreduction.hpp
/usr/include/ql/math/matrixutilities/getcovariance.hpp
/usr/include/ql/math/matrixutilities/pseudosqrt.hpp
/usr/include/ql/math/matrixutilities/qrdecomposition.hpp
/usr/include/ql/math/matrixutilities/sparseilupreconditioner.hpp
/usr/include/ql/math/matrixutilities/sparsematrix.hpp
/usr/include/ql/math/matrixutilities/svd.hpp
/usr/include/ql/math/matrixutilities/symmetricschurdecomposition.hpp
/usr/include/ql/math/matrixutilities/tapcorrelations.hpp
/usr/include/ql/math/matrixutilities/tqreigendecomposition.hpp