"Alun Harford" <de*****@alunha rford.co.ukwrot e in message
news:eA******** ******@TK2MSFTN GP04.phx.gbl...
Beemer Biker wrote:
>I cant seem to get that date into any DateTime to make my calculation
directly by subtracting "01-01-0000" from "now".
After reading this:
http://www.mathworks.com/matlabcentr...bjectType=File I
kluged up this routine that works:
// convert date time into that funny matlab serial date time that starts
at jan 1, 0000
private string DT2Matlab(DateT ime thisDT)
{
DateTime y1970 = Convert.ToDateT ime("JAN-1-1970");
thisDT = thisDT.AddDays( 719529);
// supposidly 719529 days from "0 CE" to 1970
TimeSpan ts = thisDT.Subtract (y1970);
return ts.TotalDays.To String("#.####" );
}
Seems there should be a cleaner way to calculate "Days.fraction_ of_days"
from "0 CE" all in one swoop? "01-01-0001" gives the wrong answer when
subtracting and the 0000 is a no go.
As has been said, there is no year 0, just as there is no month 0.
Thanks Alun! I read where the year "0" is just a reference point, as
explained here:
http://tinyurl.com/39b9es
quoteing "datenum is one of three conversion functions that enable you to
express dates and times in any of three formats in MATLAB: a string (or date
string), a vector of date and time components (or date vector), or as a
numeric offset from a known date in time (or serial date number). Here is an
example of a date and time expressed in the three MATLAB formats:
Date String: '24-Oct-2003 12:45:07'
Date Vector: [2003 10 24 12 45 07]
Serial Date Number: 7.3188e+005
A serial date number represents the whole and fractional number of days from
a specific date and time, where datenum('Jan-1-0000 00:00:00') returns the
number 1. (The year 0000 is merely a reference point and is not intended to
be interpreted as a real year in time.)"
I was looking for a clean (??) C# function to calculate that 7.3188e+005
Googleing I found a UTC -Matlab that used 1970. I thought there might be
a clean way to get the time span in days.fraction_o f_days out of the
DateTime function. What I have works, though it is probably not accurate
by "days in the past" let alone leap-seconds. I have a C# program that
generates a text file that is being used as input to a matlab program. The
engineer wants time in that funny number that matlab uses and was not happy
when I put out a date time string accurate down into milliseconds.
You might also want to be very careful about calendars - we've skipped
days in the past when calendars used were changed.
Alun Harford
