CMPLXF, CMPLX, CMPLXL
From cppreference.com
Defined in header
<complex.h>


float complex CMPLXF( float real, float imag );

(since C11)  
double complex CMPLX( double real, double imag );

(since C11)  
long double complex CMPLXL( long double real, long double imag );

(since C11)  
Returns a complex number composed of real
as the real part and imag
as the imaginary part. The functions are implemented as macros.
The returned value is suitable for use as an initializer for variables with static or thread storage duration, but only if real
and imag
are also suitable.
Contents 
[edit] Parameters
real    the real part of the complex number to return 
imag    the imaginary part of the complex number to return 
[edit] Return value
A complex number composed of real
and imag
as the real and imaginary parts.
[edit] Example
This section is incomplete Reason: no example 
[edit] See also
(C99)

the complex or imaginary unit constant i (macro constant) 
C++ documentation for complex
