Change the length of a specific  lunar month in windows, from 29 days to 30 days.

Posted on 2011-10-07
Last Modified: 2012-05-12
as you know, In Hegira date Lunar months some of months are 30 days, and the others are 29 days only.
How can I change the these settings for a specific month.
For example if month number 10 is 29 days at the regional date settings for the year 1432. And I need to change it to 30 days. Could I do such thing?Please help.
Notes: people depends on lunar arithmetic calculation in define these 29 & 30 settings, but in fact in many cases these calculations are defer when seeing the birth of the moon by Naked eye .
Question by:M_SOLAIMAN
    LVL 26

    Accepted Solution

    I feel your pain.
    Look here

    Since Hijiri month starts can vary, Windows may have a mechanism for it in the Regional Setting of the control panel
    Look here, although this article is about FoxPro the same will apply to Access

    The string date displayed depends upon the Regional Setting
    Get that right, and Access will follow along.

    Author Comment

    I feel your pain.
    Yes, you still remember !

    Thank you very much for the links.
    Let me tell you short story, please.
    Before windows vista, there was only this Hijri date(which is the Kuwaiti calendar. I know about it just right now from MS link you provide), where you can adjust the differences manually .
    windows vista and 7, we can see this Hijri date and a new one which is Um-AlQura calendar.
    Um-AlQura calendar is a specific for KSA, where Hijri date is common .
    There are many other countries have their specific calendar besides  the Hijri date calendar either.

    I still have two points.
    1-      You cannot adjust the Um-AlQura calendar like here in Hijri date.
    2-      In adjusting Hijri date calendar, you can  adjust today date only! I couldn't adjust a previous month, nor later month.
    The answer of point No one I found it here in  Microsoft link" However, the sight of the lunar month is different form one location to another, and the Kuwaiti algorithm used the Kuwaiti calendar. Um-AlQura algorithm was introduced to allow using the official Hijri Calendar of Saudi Arabia and to automate the date conversion without the need to adjust the offset values every time a discrepancy shows in the lunar sightings at different locations. It computes the Hijri dates based on the moonset at Makkah."
    But still the answer of the other point.
    When I use Um-AlQura calendar , you can see in the photo that is month No# 10 is 30 days
    But when I use it in ms access , it deal with it as 29 days.
    Example: when I enter 1432/10/30 and once I get out of the field, it change it to 1432/11/01.
    And this means that ms access accept month No# 10 as a 29 days only!
    Finally , I thank you Mr. Nick67 very much for your taking care.

    LVL 26

    Assisted Solution

    My friend,

    I can only read english, so I am afraid that the images do us no good.
    Hijiri dates are a difficult thing for computer networks, and a global society that depends on everyone agreeing that 1432/11/01 was today and not yesterday.
    Take the edge case of the North Pole.
    The sun begins to rise shortly before March 21, takes three days to come completely above the horizon, and stays above the horizon continuously until September 21
    It rises toward its maximum on June 21 and then takes three months to set.
    Seeing the crescent moon at sunset in such a location is not workable.

    What does local mean?
    The distance a man can travel in a day?
    I can fly from Europe to where I live and get of the airplane, nominally, 1 hour after I departed.
    The distance a community can communicate with one another?
    I could phone and speak to you directly.

    The Um-AlQura calendar is an attempt to deal with these issues.
    It is NOT adjustable.  It is based on an algorithm, and the idea that if there were observers everywhere in the world, in communication with each other, verifiable sightings to match the algorithm would occur, thereby setting the new month.  Some folks do not accept this reasoning.
    If you have your settings for the Um-AlQura calendar, it is not adjustable

    <The In adjusting Hijri date calendar, you can  adjust today date only! I couldn't adjust a previous month, nor later month.>
    You could change your computer's date and time to the month where you needed to make the adjustment, and see if you can do it retroactively that way.

    Here is another article on how Hijiri date is adjusted

    I understand your problem. If 4 years ago the regional setting said the 10th month should have 29 days, and observation said 30, you'd like Access to show the date that way.  I don't know if it can.
    <The shifts in the Hijri calendar affect the current month, and the decision to adjust it is usually made on the first day of the month. In some cases, the effect could continue throughout the next month if the next month consists of fewer than 30 days.>
    It seems that only the present month is what is adjustable.  When you look at past data, it will revert to what the regional settings algorithm said that date should have been.

    I am sorry.  I do not know if there is a way around that.

    Author Comment

    I appreciate the big effort you make to help me, and you did so. I don't know how to thank you actually.

    " The Um-AlQura calendar is an attempt to deal with these issues.
    It is NOT adjustable."

    As long as you notice that, then I'll keep go in the approach I'll mention down hear.

    What happen in KSA
    The government press distribute a 50 years calendar to deal with. 40 years are the last 40 years where the left 10 years are from today and on.
    Although it's government approved, but it's still can be changed depend on sighting of the new moon in the last year, so some years the yearly calendar for this specific  year can be changed (i.e it well differ from the same year at the pre printed book for the 50 years I mention before).

    In my point of view , the very suitable way to deal with loaner calendar such as um-alqura for instance , is to have a mapping table can mach between Hijiri and Gregorian dates day by day.
    And then you have to have a script can offset value from any moth has been changed and forward to the rest of the 50 years mapping calendar.

    There is a brilliant British guy make this approach to our site and it works excellent.(our site is IBM Mainframe using software ag natural language with ADABAS database and BD2)
    When I sow Um-alqura calendar in windows vista I feel happy, because I thought that they solve this problem in windows. But when I forced to deal with this problem right now in ms access I can see that they have something similar to the 50 years calendar with no way to offset values when needed.
    I start do such thing in ms access (you can see the attach file). But for one year only. I have no time to complete it. But now I think it's time to do so.
    In this case you will deal with Gregorian date all the time which is always accurate , and brows the matched Hijiri on forms from the mapping table only. All of the date calculations well performed on Gregorian date only.

    I hope I explain my idea right.


    Author Closing Comment

    The solution is no solution
    Thanks for help, and the good information
    LVL 26

    Expert Comment

    I am glad I could help you decide on an appraoch to the problem.
    It is a difficult one to resolve.
    I know I have the general details of the various approaches correct.
    Further reading suggests that there may be a 'calibration' of the Um-AlQura calendar by human observers once yearly.
    There is much debate, and much information about the subject--and a lot of it is contradictory.
    There may be additional information available in languages other than English--but that I cannot help you with.

    I am surprised that the Windows adjustments are only for the present month, and do not go back in time.
    I had expected that something like your correlation table would have existed for Windows in general, and been something that could have been pushed out to all the computers on a network.  I found no evidence of that in english, however.
    I was also expecting to find some evidence that when adjustments to Hijiri months occurred, that Windows Updates pushed out changes so that the past dates would remain correct, given that the adjustments in the control panel are only for the current month.
    Perhaps that occurs--but I didn't find evidence of that in english.

    Good Luck!

    Author Comment

    If I finish my small Hijri date project based on that brilliant English guy "Paul pendel" approach(we use it in a big ministry over 25 years ago), I'll find a way to give it to Microsoft to approve it. You now our man worships like Fasting Ramadan, perform pilgrim to Makah, giving Zakah(donation) and holy days(eid) all of these important worships are depending on human observers of the moon only, and not the arithmetic calculations. That’s why each year we come up with new hijiry calendar which is maybe little bet different than the main one.
    thanks a lot again

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