What did you check the results against? Do you have another mechanism for calculating the averages or are you calculating them by hand?
One follow-up comment regarding the code. As I indicated, it's a first crack, and it's not the most efficient, but it at least doesn't crash because of memory issues. While it may not seem too slow, there's room for improvement. One thing that can (and probably should) be done is to do something akin to what the LabVIEW memory manager does when needing to allocate more memory for a growing array. In the while loop when you read 1000 lines then one can also allocate a 1000 x 2500 array and append it to the 2D numeric array prior to feeding it into the for-loop. Then in the for-loop one would use a Replace Array Subset rather than a Build Array. You would need to keep track of where to do the replacing.
