 History of PI

The value of Pi has a great value in our scientific life, the importance of that value was gained through the ages. The fact that the ratio of the circumference to the diameter of a circle is constant has been known for so long that it is quite umtraceable. The first value of Pi, including the Biblical value of 3, were almost certainly found by measurement. It was also found that the Egyptians took to be a value for Pi.

The first theoretical calculation have been carried out by Archimedes (287-212 BC), he obtained the approximation: 223/71< Pi <22/7. Various people also computed Pi including:

• Ptolemy (150 AD) => 3.1416
• Tsu Chung Chi (430-501 AD) => 355/113
• Al Khawarizmi (800) => 3.1416
• Al Kashi (1430) => computed Pi to 14 places
• Viète (1540- 1603) => 9 places
• Romanus (1561-1615) => 17 places
• Van Ceulen (1600) => 35 places

The European Renaissance brought with it a whole new mathematical world. As an effect emerged the first mathematical formulae for Pi. The only difficulty in computing Pi was and still is the sheer boredom of continuing the calculation. mathematicians devoted vast amount of time and effort to this pursuit. One of these mathematicians, called Shanks, calculated Pi to 707 places in 1873. Soon after his calculations, another mathematician called De Morgan found that Shanks had made an error in the 528th place, after which all his digits were wrong! In 1949, a computer was used to calculate Pi to 2000 places.

Finally, we just want to mention how the notation of Pi arose. In 1647, Oughtred used the symbol (d/Pi) for the ratio of the diameter of a circle to its circumference. In 1697, David Gregory used (Pi/r) for the ratio of the circumference of a circle to its radius. The first to use with its present meaning was an Welsh mathematician William Jones in 1706 when he states 3.14159 andc. = Pi. Euler adopted the symbol in 1737 and it quickly became a standard notation.