RE: [Help-glpk] Time conversion functions

[Meketon, Marc]

Using the ISO 8601 standard is a good idea; while a lot of
transportation companies (notably railways in North America) treat
Sunday as day 0, I have no problem with having it be 7.

-Marc

-----Original Message-----
From: address@hidden
[mailto:address@hidden On
Behalf Of xypron
Sent: Friday, November 21, 2008 2:46 AM
To: address@hidden
Subject: RE: [Help-glpk] Time conversion functions


Hello Marc

>>Can you add a DayOfWeek(t) which returns a number 0 to 6, with
0=Sunday,
>>1=Monday, etc.

ISO 8601 defines a week date see
http://en.wikipedia.org/wiki/ISO_week_date
http://en.wikipedia.org/wiki/ISO_week_date 
Sunday has to be 7 to comply with ISO 8601 and to allow correct sorting.

>>Personally, I prefer the way that Excel and many other packages model
>>time:  It is the number of days (as a 64-bit "real" number) from some
>>base time, so 0.5 represents 12 hours from the base time.  It makes
>>differences very easy to calculate.

Calculating with seconds instead of days is not more difficult but
avoids
rounding errors. Anyway the SI unit of time is seconds.

Best regards

Xypron
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