Implemented code from Mike successfully. For other people in the same boat, make sure to disable indexing as the array enters the for loops. That held things up for a while.
About the complex extended precision, prior to that, data was being truncated, so I switched over to that format. I imagine that's a bit of overkill, eh?
Thanks to everyone here for help with this.
I need to modify this code sometime soon to deal with the third dimension I mentioned (-1, 0, and 1), I'm thinking of (somewhat wastefully) creating a 1D array that stores all those values, then somehow sort which data pairs belong in which of the three pairs of x and y axes and to average and take into account the fact that each pair of axes will not have equal numbers of data points (an x axis might read 0, 0.1, 0, 0.3, 0.4, where the third value was not entered).
Would you have any recommendations on how to implement that?
I may have to overhaul the program completely as it is since after approx. 24,000 measurements, it slows down significantly.