Kuwaiti algorithm
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The Kuwaiti algorithm is used by Microsoft to convert between Gregorian calendar dates and Islamic calendar dates.[1][2] 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.[3]
According to Robert Harry van Gent at Utrecht University, the so-called "Kuwaiti algorithm" is simply an implementation of a standard tabular Islamic calendar algorithm used in Islamic astronomical tables since the 11th century.[4]
References
- ^ Hijri Dates in SQL Server 2000 from Microsoft[dead link]
- ^ Kriegel, Alex, and Boris M. Trukhnov. SQL Bible. Indianapolis, IN: Wiley, 2008. Page 383.
- ^ The "Kuwait algorithm" in Islamic-Western Calendar Converter by Robert van Gent
- ^ "Microsoft gives no details on the mathematics of the “Kuwaiti Algorithm” but one can easily demonstrate that it is based on the standard arithmetical scheme (type Ia) which has been used in Islamic astronomical tables since the 11th century CE. Naming this algorithm the “Kuwaiti Algorithm” is thus historically incorrect and should be discontinued." Islamic-Western Calendar Converter (Based on the Arithmetical or Tabular Calendar)