cube root of negative numbers gets complex numbers? Is it a bug?

For example, cube root of -8 gets 1.0000 + 1.7321i, which should be -2 from the common sense.

Answer 1

[Roger Stafford]

It's not a bug. That complex value is one of the three valid cube roots of -8. If you want to get the real -2 value, use the 'nthroot' function:

https://www.mathworks.com/help/matlab/ref/nthroot.html

x = nthroot(-8,3)  --->  -2