Pi refers to the ratio of the circumference of a circle to the diameter on a plane. Represented by the symbol π. In ancient China, there were names such as Yuan, Yuan and Zhou. Euclid's Elements of Geometry in ancient Greece (about the beginning of the 3rd century BC) mentioned that pi was a constant, and China's ancient calculation book Zhou Bi Shu Jing (about the 2nd century BC) recorded that pi was a constant. Many approximations of pi have been used in history, most of which were obtained by experiments in the early days. For example, π = is taken from ancient Egyptian papyrus (about 1700 BC) (picture reference: edp. ust/previous/math/history/5/5 _ 51over7), which is the first geometric method to calculate pi (also called classical method or Archimedes method) and is accurate to decimal point. When Chinese mathematician Liu Hui annotated Nine Chapters Arithmetic (AD 263), he only used a circle inscribed with a regular polygon to find the approximate value of π, and also got the π value accurate to two decimal places. His method is called the secant circle method by later generations. Zu Chongzhi, a mathematician in the Northern and Southern Dynasties, further obtained the π value accurate to 7 decimal places (about the second half of the 5th century), gave the insufficient approximation of 3. 14 15926 and the excessive approximation of 3. 14 15927, and also got two approximate fractional values with a density of 355//. In the west, the secret rate was not obtained by German Otto until 1573, and it was published in the works of Dutch engineer Anthonis in 1625. In Europe, it is called the Antuoni rate. * * * Mathematician Kathy got the exact decimal value of pi 17 at the beginning of15th century, which broke the record kept by Zu Chongzhi for nearly a thousand years. 1596, the German mathematician Curran calculated the π value to 20 decimal places, and then spent his whole life calculating it to 35 decimal places of 16 10. This value is named Rudolph number after him. 1579, the French mathematician Veda gave the picture reference of the first analytic expression of π: edp.ust/previous/math/history/5/5_5/Image5_5_12b. Since then, various π-value expressions such as infinite product formula, infinite connected fraction and infinite series have appeared one after another, and the calculation accuracy of π-value has also improved rapidly. 1706, the British mathematician Mackin calculated the π value, which broke through the decimal mark of 100. 1873, another British mathematician Jean-Jacques calculated π to 707 decimal places, but his result was wrong from 528 decimal places. By 1948, Ferguson in Britain and Ronchi in the United States announced the 808-bit decimal value of π, which became the highest record of manual calculation of pi. The appearance of electronic computer makes the calculation of π value develop by leaps and bounds. From 65438 to 0949, the Army Ballistics Research Laboratory in Aberdeen, Maryland, USA used a computer (ENIAC) to calculate π value for the first time, and it suddenly reached 2037 decimal places, exceeding thousands of digits. 1989, researchers at Columbia University in the United States used Cray-2 and IBM-VF supercomputers to calculate 480 million digits after the decimal point, and then continued to calculate to 10 1 100 million digits after the decimal point, setting a new record. Besides the numerical calculation of π, its properties have also attracted many mathematicians. 176 1 year, Swiss mathematician Lambert first proved that π is an irrational number. 1794 French mathematician Legendre proved that π2 is also an irrational number. By 1882, German mathematician Lin Deman proved that π is a transcendental number for the first time, thus denying the problem of "turning a circle into a square" that has puzzled people for more than two thousand years. Others study the characteristics of π and its connection with other numbers. For example, 1929, the Soviet mathematician Gelfond proved that eπ is a transcendental number and so on.

Reference: edp.ust/previous/math/history/5/5_5/5_5_12

According to Sui Shu's law, Zu Chongzhi changed ten feet into 100 million feet, and used this as the diameter to find pi, and the abundance (exceeding the approximate value) was 3.1415927; The approximate value of loss is 3. 14 15926, and the true value of pi is between profit and loss. Sui Shu did not specify how Zu Chongzhi calculated its surplus. It is generally believed that Zu Chongzhi divided the polygon into 12288 by Liu Hui's secant method, and obtained Zu Chongzhi's famous pi inequality by Liu Hui's pi inequality: 3. 14 15926.

Originally, you could choose ~ ~ ~ What people asked was "Pi data discovered by Qiu Chong"

Guan Euclid

Lee Liu

What is a computer (ENIAC)?

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