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From: xrjjm%scint.span@VLSI.JPL.NASA.GOV
Newsgroups: comp.os.vms
Subject: Calculating Elapsed Time From DCL.
Message-ID: <870805075119.03q@VLSI.JPL.NASA.GOV>
Date: Wed, 5-Aug-87 10:51:18 EDT
Article-I.D.: VLSI.870805075119.03q
Posted: Wed Aug  5 10:51:18 1987
Date-Received: Sat, 8-Aug-87 09:14:44 EDT
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Comment:   Begin User Supplied Mail Headers.
*Site:     NASA Goddard Space Flight Center - Greenbelt, Maryland, USA.
*Position: 76 Deg. 52' 28.5" West, 38 Deg. 59' 59.8" North.
*From:     John J. McMahon, Systems Programmer, STX - ST Systems Corporation.
*Project:  COBE Science Data Room (CSDR), Code 401.1
*Reply-To: (Arpa-Internet)       XRJJM%CSDR.SPAN@JPL-VLSI.ARPA [Old Format]
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*Reply-To: (Span/Physnet/Hepnet) 6173::XRJJM = CSDR::XRJJM (Node 6.29)
*Reply-To: (TEXnet)              UTADNX::UTSPAN::CSDR::XRJJM


Lately I have been playing with the various F$xTIME commands that DCL
offers and I have noticed a couple of things that either are shortcomings,
or more likely things I have missed somewhere.

The first is converting a "Comparison" time to an "Absolute" time.  The
only difference I can find is that "Comparison" times use numeric
months, while "Absolute" uses JAN, FEB, MAR... etc.

I have a routine that wants to calculate a date 2 months back.  I take
an Absolute time as input, Convert it to Comparison, perform a calculation
(Month - 2)... then what ?  How do I convert it back to absolute ?  (In DCL).
I have considered using Delta times (Subtract 60 days or something similar)
but that doesn't fit my bill for accuracy.  I ruled out a HLL because this was 
supposed to be a Quick and Dirty job...

My second time question is, how does one calculate a delta time between two
dates (also in DCL).  I am primarily concerned with the number of days
between two dates, but knowing how to figure it out to the second would be
nice.

I have solved both of these problems already... I am just looking for the
more elegant solution.

--- Ok, next problem...  Lately I haven't seen any mail from INFO-VAX, and I
am trying to track down all of the possible failure points.  If you have
have sent mail to INFO-VAX lately, AND gotten a 'failed' message on my
address (xrjjm%csdr.span@jpl-vlsi.arpa) could you try and send me a
copy of the mail headers, or send me some mail describing the problem.
(If you can't get it to the address above, send it to ZMJJM@SCFVM.BITNET,
Internet: ZMJJM@SCFVM.BITNET@WISCVM.WISC.EDU)

Thanks & Regards,
^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v
John J. McMahon (Fast-Eddie)                     
Disclaimer: Views expressed in this letter are my own, 
            and are not meant to represent the views of my employers.