copysign
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header <math.h>
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|   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)  | 
|   C++ documentation for copysign 
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