Greek letters are capitalized and lowercase, and the English pronunciation is alpha, and the international phonetic symbol/? & ampaelig What if? /; Usually refers to angle, coefficient and angular acceleration. Everyone reading "alpha" is in line with the international phonetic alphabet, that's right.
Greek letter capital b, lowercase β, English pronunciation β, international phonetic symbol /'bet? /; Usually refers to magnetic flux coefficient, angle and coefficient. It is also appropriate to read "Beta" according to the international phonetic alphabet.
Greek letters are uppercase γ, lowercase γ, English pronunciation is gamma, and the international phonetic symbol/'g&; aeligm？ /; Usually refers to electrical conductivity, angle and specific heat capacity ratio.
The International Phonetic Alphabet strictly stipulates the principle of "one symbol and one sound", that is, "one phoneme, one symbol and one phoneme".
In languages that use pinyin schemes, the same letter usually has several pronunciations in different words. For example, the "I" in English like and lit is phonetic with international phonetic symbols, namely [ai] and [? ]。 Another example is: The A in the class (class) and the A in the state (state) in Mandarin Chinese Pinyin are [a] and [] in the international phonetic alphabet, respectively (see the entry Comparison Table of Chinese Pinyin Letters and International Phonetic Alphabet for details).
In addition, the same sound has different spellings in different languages. For example, English sh, French ch, German sch, Polish sz and Czech S are all international phonetic symbols [? ] sound.
These are the advantages of international phonetic symbols, that is, they can record and distinguish sounds more scientifically and accurately (after 2005, phonetic symbols on popular tables have 72 consonants and 32 vowels, which are generally enough to mark sounds). The arrangement of international phonetic symbols is easy to analyze and master (consonants are roughly located according to the pronunciation position and method, and vowels are located according to the position of the tongue).
Extended data:
Historical development of pi
experimental period
An ancient Babylonian stone tablet (about BC 1900 to BC 1600) clearly recorded that pi = 25/8 = 3. 125. Rhind papyrus, an ancient Egyptian cultural relic of the same period, also shows that pi is equal to the square of score 16/9, which is about 3. 1605. Egyptians seem to have known pi earlier.
British writer john tyler (178 1 _ 1864) wrote in his masterpiece The Great Pyramid: Why did you build it and who built it? ) It is pointed out that the pyramid of khufu built around 2500 BC is related to pi. For example, the ratio of the circumference to the height of a pyramid is equal to twice the pi, which is exactly equal to the ratio of the circumference to the radius of a circle.
The Brahman of Sa tabata, an ancient Indian religious masterpiece written from 800 to 600 BC, shows that pi is equal to 339/ 108, which is about 3. 139.
Geometric method period
As an ancient geometric kingdom, ancient Greece made great contributions to pi. Archimedes (287_2 12 BC), a great mathematician in ancient Greece, initiated the theoretical calculation of the approximate value of pi in human history. Starting from the unit circle, Archimedes first found that the lower bound of pi was 3 by inscribed regular hexagon, and then found that the upper bound of pi was less than 4 by pythagorean theorem.
Then, he doubled the number of sides of inscribed regular hexagon and circumscribed regular hexagon to inscribed regular hexagon 12 and circumscribed regular hexagon 12 respectively, and then improved the upper and lower bounds of pi with the help of Pythagorean theorem. He gradually doubled the number of sides inscribed with regular polygons and circumscribed with regular polygons until inscribed with regular polygons and circumscribed with regular polygons.
Finally, he found that the upper and lower bounds of pi were 223/7 1 and 22/7, respectively, and took their average value of 3. 14 185 1 as the approximate value of pi. Archimedes used the concepts of iterative algorithm and bilateral numerical approximation, which is the originator of computational mathematics.
Computer age
The appearance of electronic computer makes the calculation of π value develop by leaps and bounds. 1949, the world's first electronic numerical integrator and computer made in America was put into use at Aberdeen proving ground. The following year, Ritter wiesner, Von Newman and Mezopolis used this computer to calculate the 2037 decimal places of π.
It took the computer only 70 hours to finish the work. Deducting the time of punching in and out is equivalent to calculating single digits in two minutes on average. Five years later, IBM NORC (Naval Weapons Research Computer) calculated the 3089 decimal places of π in only 13 minutes.
With the continuous progress of science and technology, the computing speed of computers is getting faster and faster. In the sixties and seventies, with the continuous computer competition among computer scientists in the United States, Britain and France, the value of π became more and more accurate. 1973, Jean Guilloud and Martin Bouyer discovered the millionth decimal of π with the computer CDC 7600.
Baidu Encyclopedia-π (Greek alphabet)
In 2023, the Charter of Indep