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03-06-2016, 07:10 PM
Post: #5
 Dieter Senior Member Posts: 2,397 Joined: Dec 2013
RE: Back on Forum
(03-06-2016 12:43 PM)ggauny@live.fr Wrote:  I am happy to be back with you all. I was in deasease.

Ah, welcome back then. :-)

(03-06-2016 12:43 PM)ggauny@live.fr Wrote:  I submit, as present, you a little routine that it is from Joe Horn and a friend of He which optmized. It is "friday the 13" in any year in gregorian.

Thank you very much.

Here is a version that works in any date mode (d.my, m.dy or y.md). It returns all dates where the 13th is a Friday, starting at the year entered in X. One data register is required – here I chose the I-register.

Code:
LBL A FILL       ' fill stack with year CLx        ' set month = 0 LBL 01 INC X      ' increment month STO I      ' save month in I #013 x>? Y      ' month < 13 ? SKIP 004   ' then continue STO/ Y     ' else set month = 1 STO/ I     ' also do so with saved month INC Z      ' increment year in Z INC T      ' and in T →DATE      ' generate date according to mode setting ENTER WDAY       ' determine day of week #005 - x≠0?       ' is it not a Friday? SKIP 005   ' then continue CLα        ' else prepare output DROP αDATE      ' format date in Alpha #005 PROMPT     ' show date & "5" for Friday cDROP      ' DROP two levels RCL I      ' recall month GTO 01     ' and continue with next one

Example:

Code:
2010 [A]    =>  13.08.2010      [R/S]  =>  13.05.2011      [R/S]  =>  13.01.2012      [R/S]  =>  13.04.2012      [R/S]  =>  13.07.2012      [R/S]  =>  13.09.2013      [R/S]  =>  13.12.2013      [R/S]  =>  13.06.2014      [R/S]  =>  13.02.2015       ...

But somehow I do not like this trial-and-error approach. I would prefer a more analytic algorithm: determine the day of week for 13 January, calculate the next Friday 13th from this, finally add a certain number of days for the next one.

But this would get much more complicated than the current method. ;-)

Dieter
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 Messages In This Thread Back on Forum - ggauny@live.fr - 03-06-2016, 12:43 PM RE: Back on Forum - Didier Lachieze - 03-06-2016, 02:31 PM RE: Back on Forum - d b - 03-06-2016, 03:27 PM RE: Back on Forum - Sylvain Cote - 03-06-2016, 03:46 PM RE: Back on Forum - Dieter - 03-06-2016 07:10 PM RE: Back on Forum - Dwight Sturrock - 03-06-2016, 07:18 PM RE: Back on Forum - Jlouis - 03-06-2016, 07:40 PM RE: Back on Forum - rprosperi - 03-06-2016, 09:33 PM RE: Back on Forum - Etienne Victoria - 03-06-2016, 09:37 PM RE: Back on Forum - ggauny@live.fr - 03-07-2016, 09:20 AM RE: Back on Forum - ggauny@live.fr - 03-07-2016, 12:02 PM RE: Back on Forum - Dieter - 03-07-2016, 12:57 PM RE: Back on Forum - Thomas Radtke - 03-07-2016, 12:05 PM RE: Back on Forum - Dieter - 03-09-2016, 09:14 PM RE: Back on Forum - Dieter - 03-12-2016, 12:30 PM

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