`<complex.h>`

`arg`	Gives the angle of a number in the complex plane.
`complex`	Creates complex numbers.
`conj`	Returns the complex conjugate of a complex number.
`imag`	Returns the imaginary part of a complex number.
`norm`	Returns the square of the absolute value.
`polar`	Returns a complex number with a given magnitude and angle.
`real`	Returns the real part of a complex number or converts a BCD number back to float, double or long double.