Hello Fineract developers, I found a reproducible mathematical defect in the public FinanicalFunctions.nop() helper. Its non-zero-rate branch is not the algebraic inverse of the adjacent pmt() function.
Minimal round trip: rate = 0.01 periods = 12 principal = 1000 future value = 0 type = false pmt(...) = -88.848788678342 current nop(...) = 7 expected nop(...) = 12 A repository-wide search found no current call site for nop(), so I am treating this as a dormant library defect rather than claiming production loan impact. I prepared a focused correction and regression tests in a public fork: https://github.com/kadyrbekovhamit-cyber/fineract/commit/6980e1377ce2e5a1eaf0586e628b27bb64dd8c26 The proposed inverse is: A = emiAmount * (type ? 1 + rate : 1) growth = (A - rate * futureValue) / (A + rate * principal) N = log(growth) / log1p(rate) The corrected implementation passes 33/33 direct PMT/NOP round trips across zero and non-zero rates, both payment timings, and a non-zero future value. A JUnit test is included. The full Gradle target could not run locally because this checkout requires JDK 25 while the available JDK is 26. The contribution guide requires a FINERACT JIRA key in the PR title and commit. ASF JIRA does not allow guest issue creation, so could a maintainer please advise whether this should receive a ticket, or create/link one if the correction is wanted? I can then update the commit title and open the conforming PR. Best regards, Xamit Kadirbekov GERO Research
