实部real part
Involving only a complex number of which the real part is zero.
包含一个实部为零的复数的
虚部imaginary part
unitOf,relating to,or being the coefficient of the imaginary unit in a complex number.
一个复数中虚部系数的；或与之有关的；或是虚部系数的
所以虚部会用i表示