Al-Nayrizi

Abū’l-‘Abbās al-Faḍl ibn Ḥātim al-Nairīzī (Arabic: أبو العباس الفضل بن حاتم النيريزي, Latin: Anaritius, Nazirius, c. 865 – 922) was a Persian mathematician and astronomer from Nayriz, Fars Province, Iran.[1]

He flourished under al-Mu'tadid, Caliph from 892 to 902, and compiled astronomical tables, writing a book for al-Mu'tadid on atmospheric phenomena.

Nayrizi wrote commentaries on Ptolemy and Euclid. The latter were translated by the 12th century Italian scholar Gerard of Cremona. Nairizi used the so-called umbra (versa), the equivalent to the tangent, as a genuine trigonometric line, but he was anticipated in this by the Persian astronomer al-Marwazi.

He wrote a treatise on the spherical astrolabe, which is very elaborate and seems to be the best Persian work on the subject. It is divided into four books:

1. Historical and critical introduction.
2. Description of the spherical astrolabe; its superiority over plane astrolabes and all other astronomical instruments.
3. Applications.
4. Applications.

He gave a proof of the Pythagorean theorem using the Pythagorean tiling.[2]

Ibn al-Nadim mentions Nayrizi as a distinguished astronomer with eight works by him listed in his book al-Fihrist.