Move the highlighted assignment in front of the for-loop. Otherwise RA is assigned he dimension "per area" the second time the loops runs.
BTW, you don't need to strip the units from RA if you add them in your program at the correct places:
As Valery already mentioned there is no need to put the file in an archive (unless you want to pack it along with needed input data files) You may attach Mathcad sheets here directly.
Too much cluttered IMHO. And why variable k0?
After all I'd prefer using a function which later is called vectorized.
And to avoid the nested if..otherwise statements (which aren't necessary because of the special way Mathcad interprets successive if-statements) I'd prefer using return statements to quit the program as soon as possible:
