The cmath.nanj
constant represents a complex numbers with an undefined imaginary part i.e Not a Number(NaN).
Remember that in Python, a complex number is represented as a + bj where a is the real part and b is the imaginary part. If the imaginary part has a value of nanj,
it indicates that the imaginary part is undefined.
cmath.nanj
The value returned is equivalent to complex('nanj')