磁头磁阻的计算中，分别就磁芯材料的磁导率为实数和虚数的情况进行了讨论。

The calculation of head reluctance deals with two conditions in which the core material permeability is real or complex.

youdao

如果这当中有一个负数，乘积就会变成负的，如果你对一个负数开根号，你就会得到一个虚数。

If you had one negative number in it, then the product would be a negative number and, if you took a root of that, then you might get an imaginary number.

youdao

单复变量包含实数和虚数两部分，针对两个实值函数n(x) 和 v(x)的表达式为：b(x) = n(x) + iv(x)。

fullprof A complex variable has real and imaginary parts written in the form b(x) = n(x) + iv(x) for two real-valued functions n(x) and v(x)

youdao

So that's the second thing I've just highlighted here, is that I now have the ability to check whether it does the right thing.

你知道的，一个虚数,但是返回虚数就没有什么价值了,那么这是我想要强调的第二件事情。

麻省理工公开课 - 计算机科学及编程导论课程节选