SMU's system is far easier than any of that O_o.

QPA/credit hours taken = GPA

Each letter grade is worth a varying degree of 3 QPA. D = 3, C = 6, B = 9, A = 12, and a +/- .9 for +/- grades, C- = 5.1, A+ = 12.9. Each half year course is 3 credit hours, each full year course is 6 credit hours, so if you get all A+ on 6 half year course you get a GPA of 4.3 (12.9*6/18), which is the highest achievable at my university.