The problem turn out to be: files in /var/lib/dpkg/info/ reference a part of the scilab package which doesn't exist: "scilab.star"
Solution: in /var/lib/dpkg/info/postinst /var/lib/dpkg/info/prerm and /var/lib/dpkg/info/postrm, rename any mentions of scilab.star to scilab.
Results: With "sudo dpkg --purge --force-depends sivp" it should remove with the complaint "[: 53: /usr/share/scilab: unexpected operator"
This should remove it
The problem turn out to be: files in /var/lib/dpkg/info/ reference a part of the scilab package which doesn't exist: "scilab.star"
Solution: in /var/lib/ dpkg/info/ postinst /var/lib/ dpkg/info/ prerm and /var/lib/ dpkg/info/ postrm, rename any mentions of scilab.star to scilab.
Results: With "sudo dpkg --purge --force-depends sivp" it should remove with the complaint "[: 53: /usr/share/scilab: unexpected operator"
This should remove it