>>>Okay. People adapt methods which gives the result that suits the business PR as required
>>
>>And starting a discussion about which one is the best method is pretty much like starting one about religion, politics, making tea, best way to do barbecue, coffee etc: guaranteed to become heated and get nowhere.
>>
>>The practical solution for any app is to have a suite of methods and a config item somewhere where the proper one for the customer will be selected. Add methods as you find new interesting customers.
>
>That's exactly what we're doing here. The calculation method is going to be a configuration option.
>
>However, I need a good link explaining each method in details. So far in a quick google search I didn't find such a page.

Because UT is ungooglable. These methods were discussed at length here.