Re: [office-formula] Calculation Settings

[Andreas J Guelzow <aguelzow@math.concordia.ab.ca>]

On Sat, 2009-05-16 at 23:22 -0400, David A. Wheeler wrote:
> Andreas J. Guelzow wrote:
> > I think what one really should want is a specification of the serial
> > number matching 1904-1-1 and a statement how days and changes in serial
> > numbers are related.
> 
> Oh, *now* I see what you mean.  Sometimes it takes being hit over the 
> head with a 2x4 :-).  Thanks for persevering.
> 
> That's a good plan.  Would you mind proposing the specific changed text, 
> since you noticed this?  Robert Weir wants to describe the whole thing 
> as a separate type, but it'd clearly be easier to simply make this 
> clarification instead.  And even if eventually we described it as a 
> separate type (which I'm not sure we really should do since ISNUMBER() 
> etc. reveal they're really numbers), we would STILL want this clarification.

It may be a bad thing to ask a non-native-english-speaking mathematician
to come up with a formulation:
------------------------------------------------------------------------
8.4.1.1 <table:serial-date-intercept>

The <table:serial-date-intercept> element specifies the serial number of
1904/1/1, i.e. the numeric value obtained when the date 1904/1/1 is
converted into a numerical value. This numerical value is specified in
the element's table:date-value attribute.
Note: Commonly used values are 1462, 1461, 1460, 1 and 0. 

Serial numbers for dates after 1904/1/1 must equal to the serial number
for 1904/1/1 plus the number of days properly between 1904/1/1 and the
given date plus 1.

element-table:
The <table:serial-date-intercept> element is usable with the following
element: <table:calculation-settings> 8.4.1.
The <table:serial-date-intercept>> element has the following attributes:
table:date-value 17.617 and table:value-type 17.750.
The <table:serial-date-intercept> element has no child elements.

------------------------------------------------------------------------
17.617 table:date-value
The table:date-value attribute specifies the serial date intercept. The
serial date intercept is the numerical value that results if the date
value 1904/1/1 is converted into a numerical value.
The default value for this attribute is 1462.

attribute-table:date-value
The table:date-value attribute is usable with the following element:
<table:serial-date-intercept> 8.4.1.1.
The table:date-value attribute has the data type number.
------------------------------------------------------------------------

This avoids the problem that the standard asks (in the openformula
specs) to lie about the null-date to make dates after 1900/3/1 come out
correctly. This version also specifies how dates and serial numbers are
related. That is missing in the current draft.

Note that 1904/1/1 could be changed to any date after 1900/3/1. I picked
that one since some implementations will want to choose it as serial 0
or 1 and so it stands out.

Andreas
-- 
Andreas J. Guelzow
Concordia University College of Alberta