Talk:Documentation/Calc Functions/IPMT

SF Comments

(1) Summary. Suggest changing to – “Calculates the portion of a periodic payment which is interest for a fixed rate loan or annuity.”.

(2) Returns. Change “an annuity” to “a”. Clarify that the currency unit is that used to specify PV and FV. Should we state that the result is formatted as a currency by default?

(3) Arguments, Rate. Suggest changing “periodic interest rate” to “interest rate for each period”.

(4) Arguments, Period. Change “positive whole” to “real” (it does not have to be integer).

(5) Arguments, NPer. Change “, during which annuity is paid” to “for which payments are made”.

(6) Arguments, PV. Change “cash value in a sequence of payments” to “value (the initial sum borrowed or invested)”. Maybe state that PV and FV are in the same current unit?

(7) Arguments, FV. Change “desired value (future value) at the end of the periods” to desired future value (cash balance) you wish to attain at the end of the term”. Maybe state that PV and FV are in the same current unit?

(8) Arguments, Type. Change “Type is” to “Type indicates whether”. Insert “is” before “at the”. In the table, change “Maturity Date” heading to “Due Date”.

(9) Arguments, various bullets concerning NPer and Period. Please review and correct. Note that Period and Nper do not need to be integers. The key checks are that Period >= 1 and Nper >= Period.

(10) Arguments, 4th bullet. I believe that this statement is incorrect. The logic seems to be that if omitted or equal to 0, then it’s “due at the end”. Otherwise it’s “due at the beginning”. Try it to check.

(11) Additional details. The following text from the Open Office page is useful and can be included – “With a fixed rate loan, where you make a constant payment each period to pay off the loan over the term, some of each period payment is interest on the outstanding capital, and some is a repayment of capital. Over time (as you pay off capital), the interest becomes less, and the capital repayment becomes more. IPMT returns the interest in the payment of a specified period. PPMT returns the capital repaid in the payment of that period. Together they add up to the actual payment, given by PMT.

(12) Examples, 1st and 2nd examples. Change “the interest rate during the fifth period (year)” to “the interest in the payment for the fifth period”. Change “cash” to “present”. Change “The periodic payment is seven years” to “The number of payment periods is seven”. In the 1st example, change “as” to “is” (two occurrences).

(13) Related LibreOffice functions. Why is PMT linked twice? Presumably you intended to link to PPMT?

--Stevefanning (talk) 2020-11-20T13:55:29 (UTC)