麟德历晷影计算方法研究

南北朝时期关于冬夏二至晷影数值的新测定，冲破了《周礼》晷影数据的“神圣”藩篱。在这一历史背景下，李淳风于麟德历中重新测定了二十四节气晷影长度，并采用了新的数学方法—二次插值算法—计算一年中每日晷长，从而开创了中国古代历法中晷影研究的新局面。该文从历史评注、算法阐释、算例及精度校验等方面研究了李淳风的晷影算法，以期揭示李淳风的工作在中国天文学史和教学史上的意义．

A STUDY OF THE SUN'S SHADOW ALGORITHM IN THE LINDE CALENDAR

During the Northern and Southern Dynasties;the data of the Sun's shadow at the Summer and Wicker Solstices smashed the bonds of the old ones which were said to be measured by Duke Zhou. Just under that historical background; Li Chunfeng (A.D. 7th century) re-measured the Sun's data of the 24 solar terms and established a new mathematical method-quadratic interpolation-to calculate the everyday Sun's shadow in a year. His work opened up a new prospect for researches on the Sun's shadow by mathematical means. From historical commentaries; algorithm explanation;and data precision check;this paper makes a comprehensive study of the Sun's shadow observations in the Linde Calendar (665); and attempts to reveal the significance of Li's work in the histories of astronomy and mathematics of ancient China.