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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
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.