Hello Roland,
Disregard my previous email. My postdoc just explained to be that in order to calculate derivatives and such, they extend the space into minus z just a bit. This explains the negative z values. All is good. Thank you for the help!
Also, when I submitted my question to the user list, I received an automatic email saying I wasn't part of the mailing list. How would I get on this mailing list to avoid this in the future?
Best, Kyle Nelli Student of Engineering Physics University of Illinois Urbana-Champaign Cell: 847-494-5028