Al-Sijzi

Abu Sa'id Ahmed ibn Mohammed ibn Abd al-Jalil al-Sijzi (short for al-Sijistani) was a Persian astronomer and mathematician.

Sijistan from the word Sagz is a region in southeast and east in current Iran. It is mentioned in abundance in the Shahnama.

Al-Sijzi is thought to have been born around 945 CE, and lived through about 1020. His main scientific focus was astronomy. He had a deep knowledge of literature which he used to his advantage. He dedicated work to 'Adud al-Daula and the prince of Balkh. He also worked in Shiraz making astronomical observations from 969-970. He also did a lot of geometry work.

Astronomy

Al-Biruni wrote that al-Sijzi believed in a heliocentric system in which the Earth was moving and that he invented an astrolabe called the "Zuraqi" based on this idea:

Mathematics

Sijzi was a mathematician who made a special study of the intersections of conic sections and circles. He replaced the old kinematical trisection of an angle by a purely geometric solution (intersection of a circle and an equilateral hyperbola.)

Notes

References

• Hogendijk, Jan P. (1996). Al-Sijzi's Treatise on Geometrical Problem Solving. Tehran: Fatemi Publishing Co. ISBN 964-318-114-6.
• Suter, Heinrich: Die Mathematiker und Astronomen der Araber und ihre Werke (80-81, 224, 1900).