Jamshid al-Kashi

Timeline

1. c. 1380–1419Kashan · Persian IraqAl-Kashi was born in Kashan into a family of physicians or scholars. In his youth he observed lunar eclipses in his hometown and studied the Ptolemaic tradition and Persian calendrical computation. He completed works such as the Khanaka Astronomical Tables, already displaying superb sexagesimal calculating skill. After the western Timurid lands became relatively stable, his reputation reached Ulugh Beg's court in Samarkand.
2. c. 1420–1423Samarkand · TransoxianaAfter arriving in Samarkand, al-Kashi wrote to his father praising Ulugh Beg's mathematical ability and saying that among his colleagues only Qadi Zada could match him in debate. In the 1420s Ulugh Beg began building an observatory; al-Kashi took part in planning the instruments and organizing the observations, becoming the de facto first head of computation at the new institution. At court scholarly sessions, he and Qadi Zada often solved difficult problems.
3. 1424–1427Samarkand · TransoxianaIn July 1424 al-Kashi completed the Risala al-muhitiyya, computing 2π to nine sexagesimal places, equivalent to sixteen decimal places of pi, surpassing Zu Chongzhi's record of about six decimal places and remaining unsurpassed until Van Ceulen late in the sixteenth century. On 2 March 1427 he completed the Miftah al-hisab (Key of Arithmetic), for teaching astronomy, surveying, architecture, and commercial calculation, systematically treating decimal fractions and algebra.
4. 1427–1429Samarkand Observatory · SamarkandAl-Kashi continued stellar and planetary observations at the observatory, laying the computational groundwork for the later Zij-i Jadid-i Sultani. He died in Samarkand on 22 June 1429; one manuscript says he died suddenly outside the observatory, and both natural death and political murder have been proposed as causes, without resolution. The observations were then continued by Qadi Zada al-Rumi and the younger Ali Qushji, and the star catalogue was completed around 1440.