Complex number introduction
We call a number in the form of z = a+bi (both a and b are real numbers) a complex number. Where a is called the real part, b is called the imaginary part, and I is called the imaginary part. When the imaginary part of z b = 0, then z is a real number, when the imaginary part of z? When b≠0 and the real part A = 0, Z is often called pure imaginary number. Complex number field is an algebraic closure of real number field, that is, any polynomial with complex coefficients always has roots in complex number field.
The complex number was first put forward by Cardan, a scholar in Milan, Italy, in the16th century. Through the work of D'Alembert, De Moivre, Euler and Gauss, this concept was gradually accepted by mathematicians.
Complex number algorithm includes addition, subtraction, multiplication and division. The sum of two complex numbers is still a complex number, its real part is the sum of the original two complex numbers, and its imaginary part is the sum of the original two imaginary parts. The addition of complex numbers satisfies the commutative law and associative law. In addition, when a complex number is used as the base, exponent and real number of the power sum logarithm, its operation rules can be derived from the radian system of Euler formula e I θ = cos θ+I sin θ.