Circumferential symplectic (Pi) is the present value of the circumference and diameter of a circle, which is generally expressed by the Greek letter π, and is a universal mathematical constant in mathematics and physics. π is also equal to the ratio of the area of the circle to the square of the semi-meridian. Accurate calculation of geometric shapes such as circle perimeter, circle area and sphere volume is the key value. In the analysis, π can be strictly defined as the smallest positive real number x satisfying sinx=0.

Pi is written in letters (pronounced p & amp； A grave: i) indicates that it is a constant (approximately equal to 3. 14 1592654) is the ratio of the circumference of a circle to the straight meridian. It is an irrational number, that is, an infinite cycle decimal. In our daily life, we usually use 3. 14 represents the approximate calculated pi. Instead, use ten decimal places. 3。 A general calculation of 14 1592654 is enough. Even if engineers or physicists want to make more accurate calculations, they only need to take the values to a few hundred decimal places at best. 1965, JohnWallis, a British mathematician, published a book about mathematics, in which he deduced a formula that apparent pi is equal to the product of multiplication of infinite fractions. 20 15 scientists at the university of rochester found the same circular symplectic formula in the quantum mechanical calculation of hydrogen atomic energy level.