Abū’l-‘Abbās al-Faḍl ibn Ḥātim al-Nairīzī (, c. 865 – c. 922) was a Persian mathematician and astronomer from Nayriz, now in Fars Province, Iran.

Life

Little is known of al-Nairīzī, though his nisba refers to the town of Neyriz. He mentioned al-Mu'tadid, the Abbasid caliph, in his works, and so scholars have assumed that al-Nairīzī flourished in Baghdad during this period. Al-Nairīzī wrote a book for al-Mu'tadid on atmospheric phenomena. He died in c. 922.

Mathematics

Al-Nayrizi wrote a commentary to the translation in Arabic by Al-Ḥajjāj ibn Yūsuf ibn Maṭar of Euclid's Elements. Both the translation and the commentary have survived, as well as a 12th-century Latin translation by Gerard of Cremona. Al-Nayrizi's commentary contains unique extracts of two other commentaries on the Elements, produced by Hero of Alexandria and Simplicius of Cilicia. Al-Nairīzī used the umbra (versa), the equivalent to the tangent, as a genuine trigonometric line, as did the Persian astronomer al-Marwazi before him. He gave a proof of the Pythagorean theorem using the Pythagorean tiling. Al-Nayrizi gave a mathematical proof of the parallel postulate based on the assumption that parallel lines are equidistant. He wrote a treatise on an exact method for the numerical determination of the kibla and a text about a device for measuring the heights, widths, and depths.

Astronomy

Al-Nairīzī wrote a treatise on the spherical astrolabe, an elaborate work that seems to be the best Persian work on the subject. It is divided into four books: Ibn al-Nadim mentions Nayrizi as a distinguished astronomer with eight works by him listed in his book al-Fihrist. Al-Nayrizi's most important astronomical works, his commentary on Ptolemy's Almagest and both his zijes, are lost. He produced treatises on the spherical astrolabe and astrological conjunctions, both of which are extant.

Sources

Texts and translations