/usr/share/octave/site/m/vlfeat/toolbox/plotop/ is in octave-vlfeat 0.9.20+dfsg0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_cf.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_click.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_clickpoint.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_clicksegment.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_det.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_figaspect.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_linespec2prop.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_plotbox.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_plotframe.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_plotgrid.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_plotpoint.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_plotstyle.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_pr.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_printsize.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_roc.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_tightsubplot.m
/usr/share/octave/site/m/vlfeat/toolbox/plotop/vl_tpfp.m