A function whose range is in the complex numbers is said to be a complex function, or a complex-valued function.
Complex Function
See also
Complex Variable, Function, Real Function, Scalar Function, Vector FunctionExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Complex Function." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ComplexFunction.html