Al-Kashi
c. 1380 CE–c. 1429 CE · Kashan
Ghiyath al-Din Jamshid Mas'ud al-Kashi (c. 1380–1429) was one of the most accomplished mathematicians and astronomers of the medieval Islamic world. He was born in Kashan, a city in central Persia, around 1380 — the year is a traditional estimate, since no source records it directly. The first firmly dated event of his life is his observation of a lunar eclipse at Kashan in June 1406. He worked there in difficult, reportedly impoverished conditions, producing his early astronomical treatise Sullam al-sama' ("The Stairway of Heaven," 1407) and later the Khaqani Zij, a large set of astronomical tables.
Around 1420 al-Kashi was invited by the Timurid prince Ulugh Beg — himself a serious astronomer — to join the new madrasa (college) and observatory at Samarqand, in Transoxiana. There he became the institution's foremost mathematician and astronomer. In a treatise of 1424 he calculated 2π to nine sexagesimal (base-60) places, equivalent to sixteen decimal places — a precision unsurpassed for roughly 180 years. His Miftah al-Hisab ("Key to Arithmetic," 1427) is a landmark on decimal fractions and computational methods; a trigonometric relation he used is still called "al-Kashi's theorem" in France.
He died at Samarqand on 22 June 1429. Sources disagree on the cause: some later reports claim he was murdered, possibly on Ulugh Beg's orders, while others hold he died naturally. Ulugh Beg is reported to have praised him as a remarkable scientist who could solve the most difficult problems.
Did you know?
Pi to sixteen decimals, by hand, in 1424
The Persian mathematician al-Kashi (c. 1380–1429), working at Samarkand, computed pi to an accuracy equivalent to sixteen decimal places in his Treatise on the Circumference (1424). It was the most precise value known anywhere, and it held the record for roughly 170 years, until Ludolph van Ceulen surpassed it in 1596.
How we know
Jamshīd al-Kāshī (b. c.1380 Kashan – d. 22 June 1429 Samarkand); Risāla al-muḥīṭiyya (Treatise on the Circumference), July 1424, π to ~16 decimal digits via a 3×2^28-sided polygon; unsurpassed until van Ceulen's 20 digits in 1596 (172 yrs). Refs: Britannica, MacTutor (St Andrews), Wikipedia.
Life journeyclick any stop, or use ←/→Trace on the map →
Kashan
What they did here
Al-Kashi was born in Kashan, central Persia, around 1380 (a traditional estimate; the exact year is not recorded). His earliest firmly dated activity is a lunar eclipse he observed there in June 1406, and his early works — the treatise Sullam al-sama' (1407) and the Khaqani Zij astronomical tables — date from his Kashan period.
About Kashan
Kashan, on the edge of the central Iranian desert, was a town noted for its ceramics (whence the term 'kashi' for tilework) and a centre of Shi'i learning. The philosopher and traditionist al-Fayd al-Kashani (d. 1680), a student of Mulla Sadra and major figure of the Safavid intellectual world, took his nisba from the city.
The world in their lifetime
Thinkers and teachers of other traditions whose lives overlapped with Al-Kashi’s — a glimpse of the wider world they lived in. Drawn purely from recorded birth and death years.
Jewish world
Christian world
Works
No works attributed in the corpus yet.