Qin Jiushao

Qin Jiushao (Chinese: 秦九韶; pinyin: Qín Jiǔshào; Wade–Giles: Ch’in Chiu-Shao, ca. 1202–1261), courtesy name Daogu (道古), was a Chinese mathematician.

Biography

He was born in Ziyang, Sichuan, his ancestry was from Shandong, and is now regarded as one of the greatest mathematicians of the 13th century. This is particularly remarkable, as Qin did not devote his life to mathematics. He was accomplished in many other fields, however, and held a series of bureaucratic positions in several Chinese provinces.

Qin’s reputation as a lies in the Shùshū Jiǔzhāng (“Mathematical Treatise in Nine Sections”), issued in 1247. The treatise covered matters that ranged from indeterminate analysis to military matters and surveying. In the treatise, Qin included a version of the Chinese remainder theorem, which used algorithms to solve problems. In geometry, he discovered “Qin Jiushao's formula” in finding the area of a triangle with given length of three sides. This is the same as Heron’s formula, discovered earlier.

Qin recorded the earliest explanation of how Chinese calendar experts calculated astronomical data according to the timing of the winter solstice. Among his accomplishments are introducing techniques for solving (arbitrary order) algebraic equations (A numerical algorithm based on Horner's method), finding sums of arithmetic series, and solving linear systems. He also introduced the use of the zero symbol in Chinese mathematics.

After he completed his work on mathematics, he went into politics. He was boastful, corrupt, accused of bribery and of poisoning his enemies, so several times he was relieved of his duties, and put in 'suspension'. Even so, he managed to become very wealthy. In contrast to many ancient mathematicians, he was reputedly not very wise and bored quickly with maths, which may be why he focused so little of his life on its study.

Main work

• Shushu Jiuzhang (Mathematical Treatise in Nine Sections) (1247)

References

• Guo, Shuchun, "Qin Jiushao". Encyclopedia of China (Mathematics Volume), 1st ed.
• Qin Jiushao ,[1]. (Chinese History Timeline), 2007.
• Ulrich Libbrecht: Chinese Mathematics in the Thirteen Century(The Shu-Shu-Chiu-Chang of Chin Chiu shao) Dover Publication ISBN 0486446190

External links

• O'Connor, John J.; Robertson, Edmund F., "Qin Jiushao", MacTutor History of Mathematics archive, University of St Andrews, http://www-history.mcs.st-andrews.ac.uk/Biographies/Qin_Jiushao.html .
• Simon Fraser University biography for “Qin Jiushao”

Persondata
Name	Qin, Jiushao
Alternative names
Short description
Date of birth	1201
Place of birth
Date of death	1261
Place of death