Kuwaiti algorithm
Encyclopedia
The Kuwaiti algorithm is used by Microsoft
to convert between Gregorian calendar
dates and Islamic calendar
dates. There is no fixed correspondence defined in advance between the Gregorian solar calendar
and the Islamic lunar calendar
, since the latter is defined by the visibility of the new moon by religious authorities and can therefore vary by a day or two, depending on the particular Islamic authority, weather conditions, and other variables. As an attempt to make conversions between the calendars somewhat predictable, Microsoft claims to have created this algorithm
based on statistical analysis of historical data from Kuwait
. However, its results are identical to a variation of the tabular Islamic calendar
, which was introduced by Muslim astronomers around the eighth century.
Inevitably, any arithmetic algorithm is imprecise, and results often differ by a day or two from observation or complex calculation.
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
to convert between Gregorian calendar
Gregorian calendar
The Gregorian calendar, also known as the Western calendar, or Christian calendar, is the internationally accepted civil calendar. It was introduced by Pope Gregory XIII, after whom the calendar was named, by a decree signed on 24 February 1582, a papal bull known by its opening words Inter...
dates and Islamic calendar
Islamic calendar
The Hijri calendar , also known as the Muslim calendar or Islamic calendar , is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. It is used to date events in many Muslim countries , and used by Muslims everywhere to determine the proper day on which to celebrate Islamic...
dates. There is no fixed correspondence defined in advance between the Gregorian solar calendar
Solar calendar
A solar calendar is a calendar whose dates indicate the position of the earth on its revolution around the sun .-Tropical solar calendars:...
and the Islamic lunar calendar
Lunar calendar
A lunar calendar is a calendar that is based on cycles of the lunar phase. A common purely lunar calendar is the Islamic calendar or Hijri calendar. A feature of the Islamic calendar is that a year is always 12 months, so the months are not linked with the seasons and drift each solar year by 11 to...
, since the latter is defined by the visibility of the new moon by religious authorities and can therefore vary by a day or two, depending on the particular Islamic authority, weather conditions, and other variables. As an attempt to make conversions between the calendars somewhat predictable, Microsoft claims to have created this algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
based on statistical analysis of historical data from Kuwait
Kuwait
The State of Kuwait is a sovereign Arab state situated in the north-east of the Arabian Peninsula in Western Asia. It is bordered by Saudi Arabia to the south at Khafji, and Iraq to the north at Basra. It lies on the north-western shore of the Persian Gulf. The name Kuwait is derived from the...
. However, its results are identical to a variation of the tabular Islamic calendar
Tabular Islamic calendar
The Tabular Islamic calendar is a rule-based variation of the Islamic calendar. It has the same numbering of years and months, but the months are determined by arithmetic rules rather than by observation or astronomical calculations...
, which was introduced by Muslim astronomers around the eighth century.
Inevitably, any arithmetic algorithm is imprecise, and results often differ by a day or two from observation or complex calculation.