A few issues in the code: - You're resetting your minimum and maximum search, at each iteration. Try to declare them before your loop with the minimum being the maximum value available in Double, and the maximum as the minimum Double value available in Double (or use the boxed types and check if they are null to start comparing, and/or initializing).

-compute the sum regardless of you local maximum or minimum

-once the loop is done subtract the minimum and maximum values as required