lets say I have a basic text file that looks like this:
91 N 91 H 1.48 95 N 95 H -0.26 97 N 97 H 1.79 98 N 98 H -0.76
I want to change columns 1 and 3 so that the integer values are n-3 like this:
88 N 88 H 1.48 92 N 92 H -0.26 94 N 94 H 1.79 95 N 95 H -0.76
I realize awk is probably the best way to do this, but i have no idea how to get awk to apply a formula to a column, or for that matter for awk to treat a column as integer values. Is there a simple script that could do this? Also on that note: what a good comprehensive guide to how to use awk, because the ones I've seen so far are just example scripts of how to do things.