I call on fintech specialists - Implementation of the PSK (full cost of the loan) under 229-FZ?

Question

Algorithms

Colleagues, good afternoon. Faced with the task of implementing the calculation of the full cost of the loan according to 229-FZ (this is the beast itself - www.consultant.ru/document/cons_doc_LAW_165818/3d0... ).
At first glance, nothing complicated, but the numbers do not fight with reality, solutions from the Internet either do not work at all, or are written for some special cases and also, in general, do not work.
Are there any fintech specialists who have already solved a similar problem in C# and have a confirmed implementation that has been adopted in a financial organization (bank, MFI - it doesn’t matter)? I really need advice for cookies or some other bonuses.

Answer 1

The formula is quite simple, what's the problem?

Answer 2

Alexander, greetings. The formula is like three kopecks, but the problem is how to interpret the instructions to the Federal Law. For example, NBP is an integer or fractional number, or Ek - how to correctly calculate based on the wording "Ek is equal to the period expressed in fractions of the base period, from the end of the qk-th base period to the date of the k-th cash flow (k = 2, as the first stream according to the schedule, as a rule, is the issuance of a loan)".
We tried different options from the many available - different numbers are obtained. It is not clear which are correct - therefore I am looking for a specialist who has already solved and SOLVED this problem.