sum(ATretreive{1,7:10})
ATretrieve is a cell . Using index {1,7:10} is cell expansion, and is going to produce a comma-separated list, just as if you had invoked
sum(ATretreive{1,7}, ATretreive{1,8}, ATretreive{1,9}, ATretreive{1,10})
That is too many non-option arguments for sum()
I suspect what you want is
mean(cell2mat(ATretrieve(1,7:10)), 2) * 100 - 273
but you need to figure out whether you want the sum to be by row or by column; the version with mean() here is by row under the guess that the division by 4 corresponds to division by number of columns.
