Shamsuddin al-Samarkandi

Shamsuddin Mahammad ibn Ashraf al-Hussein al-Samarkandi ( Arabic. السمرقندي , second half of the 13th century) is a Central Asian mathematician and astronomer, a student of al-Khazini . He worked at the Maragha Observatory under the leadership of Nasir al-Din at-Tusi .

The treatise "Proposals of justification" is devoted to the explanation of a number of sentences of I and II books of the "Beginnings" of Euclid . This work has been preserved in many manuscripts, mostly with commentaries by Kazi-zade ar-Rumi . Unlike Euclid, al-Samarkandi widely uses motion in geometry, believing that the proof with the help of the motion is “produced in the true way”.

This treatise contains yet another attempt to prove the fifth postulate of Euclid, similar to that of al-Jawhari . It was previously believed that this attempt belongs to al-Samarkandi himself, but then it was found out that its author is al-Abkhari . It begins with the suggestion that in the corner you can draw infinitely many “chords”, which are the bases of an isosceles triangle. The author mistakenly believes that something else directly follows from this sentence, according to which through an arbitrary point inside the corner you can draw a straight line intersecting both sides of this corner.

As-Samarkandi also wrote A Treatise on the Compass for Conical Sections, a commentary on Claudius Ptolemy's Almagest , A Memo on Astronomy. The star calendar compiled by al-Samarkandi for 1267 has survived.