/usr/include/ITK-4.5/lapack/single/ is in libinsighttoolkit4-dev 4.5.0-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ITK-4.5/lapack/single/sgeqpf.h
/usr/include/ITK-4.5/lapack/single/sgeqr2.h
/usr/include/ITK-4.5/lapack/single/sgerq2.h
/usr/include/ITK-4.5/lapack/single/sggsvd.h
/usr/include/ITK-4.5/lapack/single/sggsvp.h
/usr/include/ITK-4.5/lapack/single/slacpy.h
/usr/include/ITK-4.5/lapack/single/slags2.h
/usr/include/ITK-4.5/lapack/single/slange.h
/usr/include/ITK-4.5/lapack/single/slapll.h
/usr/include/ITK-4.5/lapack/single/slapmt.h
/usr/include/ITK-4.5/lapack/single/slapy2.h
/usr/include/ITK-4.5/lapack/single/slarf.h
/usr/include/ITK-4.5/lapack/single/slarfg.h
/usr/include/ITK-4.5/lapack/single/slartg.h
/usr/include/ITK-4.5/lapack/single/slas2.h
/usr/include/ITK-4.5/lapack/single/slaset.h
/usr/include/ITK-4.5/lapack/single/slassq.h
/usr/include/ITK-4.5/lapack/single/slasv2.h
/usr/include/ITK-4.5/lapack/single/sorg2r.h
/usr/include/ITK-4.5/lapack/single/sorm2r.h
/usr/include/ITK-4.5/lapack/single/sormr2.h
/usr/include/ITK-4.5/lapack/single/stgsja.h