Stefan, what happened when you tried this:
m = sort(rand(1, 7)); % create sample data
mDiff = diff(m)
meanSquareOfDiffs = mean(mDiff .^ 2)
ms = sqrt(meanSquareOfDiffs)
It seems pretty easy if you just take it a step at a dime. Heck, you could even have used a for loop if you really got stuck and needed a simple brute force method. What did you try that didn't work?
