/usr/share/octave/packages/symbolic-2.6.0/@double/ is in octave-symbolic 2.6.0-3build1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/octave/packages/symbolic-2.6.0/@double/coshint.m
/usr/share/octave/packages/symbolic-2.6.0/@double/cosint.m
/usr/share/octave/packages/symbolic-2.6.0/@double/dilog.m
/usr/share/octave/packages/symbolic-2.6.0/@double/fresnelc.m
/usr/share/octave/packages/symbolic-2.6.0/@double/fresnels.m
/usr/share/octave/packages/symbolic-2.6.0/@double/harmonic.m
/usr/share/octave/packages/symbolic-2.6.0/@double/logint.m
/usr/share/octave/packages/symbolic-2.6.0/@double/polylog.m
/usr/share/octave/packages/symbolic-2.6.0/@double/sinhint.m
/usr/share/octave/packages/symbolic-2.6.0/@double/sinint.m
/usr/share/octave/packages/symbolic-2.6.0/@double/zeta.m