copysign
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header  
<math.h>
  | 
||
|   float       copysignf( float x, float y ); 
 | 
(since C99) | |
|   double      copysign( double x, double y ); 
 | 
(since C99) | |
|   long double copysignl( long double x, long double y ); 
 | 
(since C99) | |
Composes a floating point value with the magnitude of x and the sign of y. 
[edit] Parameters
| x, y | - | floating point values | 
[edit] Return value
Floating point value with the magnitude of x and the sign of y
[edit] See also
|    absolute value of a floating point value (|x|)   (function)  | 
|
|    (C99) 
 | 
   checks if the given number is negative   (function)  |