having briefly been reviewed the historical process of changing the formulae for determining the times of islamic prayers, two newly found formulae and a new rule for establishing the times of prayers would be discussed. these matters have been exploited from four texts, still preserved as manuscript: (1) siyyid ¾?y? al-d?n sh?shtar?’s ¼ad b?b dar macrifa al-a½??rl?b, (2) b?r?n?’s ’ist?c?b f? c...

dar bayan-i ?istikhradj-i djayb-i yik daradja is a persian treatise by an anonymous author. the author’s purpose is to describe and explain a method for the determination of the sine of one degree according to ??sh ch?’s persian commentary on ulugh beg’s z?dj, and ????z?da’s arabic treatise entitled ris?la fi ?istikhradj djayb daradja wahida. kad?zada’s work, extant in several manuscripts, is, ...

the treatise entitled “arithmetic in astronomy”, which is edited and commented upon in this paper, is part of an old manuscript collection preserved in the national library of bosnia and herzegovina. at the end of this treatise there are some phrases in arabic which show that the treatise was originally part of a persian book written by ʿalī al-qūshchī. this manuscript is, in fact, an abridged ...

manuscript no. 3447 in national library of tabriz is a persian treatise which covers arithmetic, geometry, algebra, hayʾa and the topic of “masses and distances. the redaction of the text has been finished in 670ah/1271ad but we don’t know anything about the author of the treatise. in the two first chapters of his treatise (on arithmetic) the unknown author draws upon ʿabd al-qāhir al-baghdādī’...

In this paper, we study Ghiyath al-Din Jamshid al-Kashi's (1380-1429 A.D.) main mathematical achievements. We discuss his al-Risala al-muhitiyya ("The Treatise on the Circumference"), Risala al-watar wa'l-jaib ("The Treatise on the Chord and Sine"), and Miftah al-hisab ("The Key of Arithmetic"). In particular, we look at al-Kashi's fundamental theorem, his calcula...

the mathematical treatises known as ta?r?r al-mutawassi??t, “revision of the middle books”, are a collection of greek and arabic treatises which were re-edited by na??r al-d?n al-??s?. this paper explores the nature of the editorial work ??s? did, showing that it is not a simple rendering of the original text but that it involves major revisions and in fact original additions. for the first tim...