Sanad ibn Ali was either an
Iraqi Jewish or a Sindhi from
Mansura, capital of
Arab Sind. He is known to have translated and modified the
Zij al-Sindhind. The Zij al-Sindhind was the first astronomical table ever introduced in the
Muslim World. As a mathematician Sanad ibn ʿAlī was a colleague of
al-Khwarizmi and worked closely with
Yaqūb ibn Tāriq together they calculated the
diameter of the
Earth and other astronomical bodies. He also wrote a commentary on
Kitāb al-ğabr wa-l-muqābala and helped prove the works of
al-Khwarizmi. The
decimal point notation to the
Arabic numerals was introduced by Sanad ibn Ali. According to
Ibn Abi Usaibia: the
Banū Mūsā brothers out of sheer professional jealousy kept him away from
Abbasid Caliph al-Mutawakkil at his new capital
Samarra and had caused Sanad ibn ʿAlī to be sent away to
Baghdad. Both
Ja'far Muhammad ibn Mūsā ibn Shākir and
Ahmad ibn Mūsā ibn Shākir delegated the work of digging a great
canal instead to
Al-Farghani and thus ignoring Sanad ibn ʿAlī, the better engineer.
Al-Farghani committed a great error, making the beginning of the canal deeper than the rest and water never reached the new garrison of ''Al-Ja'fariya''. News of this greatly angered
al-Mutawakkil and the two
Banū Mūsā brothers were saved from severe punishment only by the gracious willingness of Sanad ibn ʿAlī, to vouch the corrections of
Al-Farghani's calculations thus risking his own welfare and possibly his life. ==References==