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The length of real solar year has some variations because of different factors in a way that is very difficult to compute it for each year. The solar calendar there fore must be based on the average length of the solar year. This length i.e tropical year is not an integer ( 365.24219879 days). Thus in solar calendar, we must make use of some special intercalation in order to get the length of calendar year as much close to the length of natural year as possible.
The present Iranian calendar is a solar one . but the law is silent about the length of solar year and the method of intercalation , the fact that has brought about discrepancies among the experts in Iranian calendar
Believing in the necessity of accepting the average length of solar year the author has tried to find the best intercalation and appropriate cycle(s) by using a computer program as the result of these computations , a 2820-year cycle . with its special system of leap years. Is the best possible since it prepares a cycle for any ideal solar calendar , including the present Iranian calendar .the outhor claims that this cycle ( with its method of intercalation ) would put an end to discrepancies anong the scholars