Greek letters, uppercase δ, lowercase δ. In mathematics or physics, the capitalized delta is used to represent the incremental symbol. Lowercase is usually used to represent variables or symbols in higher mathematics. ξ Pronunciation Cauchy. Capital ξ, lowercase ξ, is the fourteenth Greek letter.
Kroneck δ, that is, Croneker function (also known as Croneker δ function, Kroneck δ, Croneker symbol) δij is a binary function named after German mathematician Leopold Kronecker. The independent variable (input value) of Kronecker function is generally two integers. If they are equal, the output value is 1, otherwise it is 0.
The extended data can not be regarded as a function strictly, because there is no function that meets the above conditions. In mathematics, people introduce the concept of generalized function into this kind of function. In generalized function theory, the exact meaning of δ function should be understood in the sense of integration.
In practical application, the δ function always appears with the integral? . δ distribution has important applications in partial differential equations, mathematical and physical methods, Fourier analysis and probability theory.