Proposed changes to spreadsheet functions YEAR, MONTH, DAY, HOUR, MINUTE, SECOND and other related

[Mike Kaganski <mikekaganski@hotmail.com>]

Hi!

As mentioned in [1], there is a problem in the OASIS OpenFormula 
standard (as of v.1.3 [2]). The spreadsheet functions YEAR, MONTH, DAY, 
HOUR, MINUTE are defined in such a way that for any given value of time, 
they discard fractions of respective time part: e.g., MINUTE would only 
return whole number of minutes contained in the parameter, discarding 
any fraction of a minute, no matter how close it is to 1. On the other 
hand, spreadsheet function SECOND is defined to round the number of 
seconds in minute fraction, thus it may return a number that is greater 
by 1 compared to the whole number of seconds actually contained in the 
minute fraction.

Furthermore, SECOND is defined to return 0 through 59 (never 60), but to 
use formula equivalent to ROUND(MinuteFraction * 60). Here is the first 
minor inconsistency: ROUND(MinuteFraction * 60) results in numbers 0 
through 60, not through 59.

It is impossible to modify the definition of SECOND to return 0 through 
60, because it would then become inconsistent with other spreadsheet 
software, introducing major interoperability problems. Correcting the 
equivalent formula to result in 0 through 59, like 
"MOD(ROUND(MinuteFraction * 60), 60)", brings us to the next inconsistency:

ÂÂÂ For all values of TimeParam T which have (MinuteFraction * 60) 
between 59.5 and 60.0, the set of functions:

 Â Â =YEAR(T) &"-"& MONTH(T) &"-"& DAY(T) &" "& HOUR(T) &":"& 
MINUTE(T) &":"& SECOND(T)

ÂÂÂ results in an ISO date-time string that is off by ~1 minute 
(actually, exactly by value of (MinuteFraction * 60) seconds).

This happens because value returned by SECOND will be 0 (zero), as if 
the next minute has already started, while all other functions return 
values of the minute, hour, day, ... that are still active for T.

For instance, for T corresponding for 2020-09-15 15:23:59.60, the result 
of the mentioned formula would be "2020-9-15 15:23:0".

It is impossible to change definition of SECOND to discard fraction of a 
second (for consistency with other functions), because then it would 
again be inconsistent with other spreadsheet software. So the only 
solution is to re-define the other functions to be consistent with 
(improved) SECOND definition, like this:

ÂÂÂ * Proposed improvement for SECOND(TimeParam T): 
Second=MOD(ROUND(T*86400);60)

ÂÂÂ * Proposed change for MINUTE(TimeParam T): 
Minute=(MOD(ROUND(T*86400);3600)-SECOND(T))/60

ÂÂÂ ... etc.

This would not only make the functions consistent within the standard, 
but also with other spreadsheet software.

[1] https://bugs.documentfoundation.org/show_bug.cgi?id=136615#c0

[2] 
https://docs.oasis-open.org/office/OpenDocument/v1.3/cs01/part4-formula/OpenDocument-v1.3-cs01-part4-formula.html#__RefHeading__1018202_715980110


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Best regards,

Mike Kaganski