std::polar(std::complex)
From cppreference.com
                    
                                        
                    
                    
                                                            
                    | Defined in header <complex>
  | ||
| template< class T >  complex<T> polar( const T& rho, const T& theta = 0 ); | ||
Returns a complex number with magnitude rho and phase angle theta.
[edit] Parameters
| rho | - | magnitude | 
| theta | - | angle | 
[edit] Return value
a complex number determined by rho and theta
[edit] See also
| returns the phase angle (function template) | |
| returns the magnitude of a complex number (function template) | |