The Matlab Particle Tracking Code origanally developed by Daniel Blair and Eric Dufresne, based on the IDL lagorythms developed by David Grier, John Crocker and Eric Weeks.
Origanal Matlab code is distrubuted at https://site.physics.georgetown.edu/matlab/
Origanal IDL code is distributed at https://physics.emory.edu/faculty/weeks/idl/