std::copysign

From Cppreference

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Defined in header <cmath>
float       copysign( float x, float y );		(C++11 feature)
double      copysign( double x, double y );		(C++11 feature)
long double copysign( long double x, long double y );		(C++11 feature)

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

abs(float) fabs	absolute value of an absolute value of an floating point value (|x|) (function)
signbit (C++11)	checks if the given number is negative (function)