C/math.h/copysign

copysign: gives val the same sign as signval, and return the result

<source lang="cpp">

//Declaration: float copysignf(float val, float signval);

              double copysign(double val, double signval); 
              long double copysignl(long double val, long double signval);  
 #include <math.h>
 #include <stdio.h>
 int main(void)
 {
   printf("%f", copysignf(1.0, -2.0));
  
 }
        

/* -1.000000*/

      </source>