TheSwamp

Code Red => AutoLISP (Vanilla / Visual) => Topic started by: Mark on November 17, 2003, 09:37:02 AM

Title: ACAD variable CDATE
Post by: Mark on November 17, 2003, 09:37:02 AM

Does CDATE return the hour using a 24 hr. clock or a 12 hr. clock? I can't seem to find that.  :?

Title: ACAD variable CDATE
Post by: JohnK on November 17, 2003, 09:42:00 AM

I dont have acad on my laptop but i think it returns the 24 hr clock. But dont quote me on that untill someone else quotes me on that.

Title: ACAD variable CDATE
Post by: SMadsen on November 17, 2003, 09:43:20 AM

CDATE is in 24 hr. clock in the format YYYYMMDD.HHMMSShsec

DATE is in julian format, where the fraction is in "fraction of a day" (seconds since midnight). So it's neither 12 hr. clock nor 24 hr. but a 86,400 second clock  :)

Title: ACAD variable CDATE
Post by: daron on November 17, 2003, 09:43:50 AM

I think it's a 24 hr. clock. In fact, I'm sure of it, because it doesn't differentiate between am and pm.

Title: ACAD variable CDATE
Post by: Mark on November 17, 2003, 09:54:25 AM

>julian format
I wish I understood that one. I was reading about  it this morning. whoosh right over my head.

thanks to all.

Title: ACAD variable CDATE
Post by: rugaroo on November 17, 2003, 10:20:50 AM

Mark -

I agree with you on the whoosh part...Here is a link (http://www.onlineconversion.com/julian_date.htm) to help convert, but honestly there is no down to earth simple definition....at least that I could see.

Title: ACAD variable CDATE
Post by: SMadsen on November 17, 2003, 10:34:40 AM

There's a very simple definition of julian dates: 1st of January 4713 BC at 12:00:00 GMT (Greenwich) is Day 0.
Julian dates are merely incremented by 1 for each day at noon GMT. As for fractions, a day is divided into 1/24's. So 1 hour is 0.041666667, 12 hours is 0.5 etc. Couldn't be simpler.

Try inputting 1473 BCE, Jan. 1st into the calculator at the link above.

(notice: the definition is simple .. the calculations are another matter :) )