  This is a revised version of the lecture notes prepared for the workshop on
"Plane quartics, Scorza map and related topics", held in Catania, January
19-21, 2016. The last section contains eight Macaulay2 scripts on theta
characteristics and the Scorza map, with a tutorial. The first sections give an
introduction to these scripts. The tutorial contains a list of the 36 Scorza
preimages of the Edge quartic.
