Yusuf al-Mu'taman ibn Hud

Abu Amir Yusuf ibn Ahmad ibn Hud (Arabic: أبو عامر يوسف بن أحمد بن هود, romanized: Abū ʿĀmir Yūsuf ibn Aḥmad ibn Hūd; died c. 1085), more commonly known as al-Mu'taman, was a mathematician, and also one of the kings of the Taifa of Zaragoza. The name al-Mu'taman is itself a shortening of his full regnal name al-Mu'taman Billah (Arabic: المؤتمن بالله, romanized: al-Mūʾtaman bi-ʾLlāh, lit. 'Trustee through God').

Al-Mu'taman was the third king of the Banu Hud dynasty, reigning from 1081 to 1085, at the height of power of Muslim Zaragoza, following the thriving period of his father Ahmad al-Muqtadir. He continued his father's efforts and created around him a court of intellectuals, living in the beautiful palace of Aljafería, nicknamed as "the palace of joy".

As king, Al-Mu'taman was a patron of science, philosophy and arts, and was himself a scholar of considerable accomplishment. He knew astrology, philosophy, and especially mathematics, a discipline in which he wrote the most important treatise to come out of the al-Andalus region in the 11th century,^[1] the Kitab al-Istikmal ("Book of Perfection").