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*Subject*: **ODFF: yet more suggestions**

*From*:**"David King" <openoffice@drking.plus.com>***To*: office-comment@lists.oasis-open.org*Date*: Thu, 31 Jul 2008 21:30:12 +0100

Hello all Another list for the archive... PMT * Constraints should have Nper>0 and integer * For clarity, should specify that with PayType=1 the first payment is made on the same day the loan is taken out. * The formula is unstable at very low rates. Better to use an approximation - but Calc at least does not do so, and will produce #VALUE! errors. Excel 97 similarly gives #DIV/0! CORREL Currently as defined, also allows different dimensions for the two parameters - if this is intended should be explicitly stated (NB Calc expects the same dims). Also it's a redundant function - it's identical to Pearson. PV Payment can be omitted if fv is given. DISC should divide by YEARFRAC, not multiply I think. SYD "sum-of-years' digits method" *This phrase appears to be copied from Excel. I'd suggest either "sum- of-years' digits method" or "sum of years'-digits method". * Formula is at: http://wiki.services.openoffice.org/w/index.php?title=Documentation/How_ Tos/Calc :_SYD_function DDB "I don't know how to put this into the equations." See: http://wiki.services.openoffice.org/wiki/Documentation/How_Tos/Calc:_DDB _functio n DOLLARDE Does not return currency; returns a number. TBILLEQ * Excel gives the formula: "TBILLEQ is calculated as TBILLEQ = (365 x rate)/360-(rate x DSM), where DSM is the number of days between settlement and maturity computed according to the 360 days per year basis." That's wrong - should be (365 x rate)/[360-(rate x DSM)]. Also: using the 360 day year is vital information which needs to be included. * "bond-equivalent yield for a treasury bill" is probably lifted from Excel's Help, and comes across as jargon; needs more explanation, especially for non-US people. ISPMT "amortized investment" is jargon, possibly not readily understood except in the US. It gets no useful hits from Google. ODDFYIELD doesn't need to say "yield per 100 units" - yield is irrespective of this. XNPV Excel documentation gives the formula. It's based on 365 days only. They've missed out a minus sign. More detail is required to define this function. Excel's help also seems to have an error - I don't think it is *necessary* to have a negative entry - first entry could be a payment. The day count appears to be the actual day count (366 in a leap year). FTEST "Summary: Returns the result of an F test (the probability that two datasets have come from the same total population)" Excel says it tests the probability that the *variances* are not significantly different (which is not the same as coming from the same total population). "An F-test returns the one-tailed probability" Excel currently describes this as the 2-tailed probability. I believe that is correct (see http://www.coventry.ac.uk/ec/~nhunt/pottel.pdf). Old versions of Excel eg 97 describe it as one tailed. It would be worth someone with real knowledge checking this out. VDB http://wiki.services.openoffice.org/wiki/Documentation/How_Tos/Calc:_VDB _functio n has a rather more detailed explanation, and a link to (different) bugs in Calc and Excel. Hope it's still helpful.... David King

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