I would vote for using functions to do the jobs. Especially if you need to calculate a difference vector more than once.
Here are two examples - basically reflecting the two different methods shown by Luc an Fred.
but programming is,
as are very advanced functions like the Re() and Im() functions (and Bessel functions, statistics, data analysis, curvefitting and smoothing, design of experiments, differential equations, signal- and image processing functions),
plots other than XY-plots,
Furtunately the complex conjugate operator works, so Re() and Im() are easily defined.
No, those things are not considered "premium".
Luc was referring to my functions which would not work in Express.
Your version with ranges and indexing will of course work as well in Prime Express.
BTW, you can easily try what Express is like. Just point your licensed version to an invalid licence (any text file or the like will do).
Yes, I can switch simply by pointing Prime to an invalid file as license file.
At the moment I am working on a machine with a network flex license so I had additionally plug out the network cable because we set the installation vi environent variable so it looks for one flexlm server after the othe for a license if licensing fails.
When I work on a machine with a local single user license bound to the MAC, its as simple as pointing Prime to an invalid file (a non-existing file will not do) and you have to remember the name and location of the valid license file to be able to switch back, of course 😉