fabs(), fabsf() - floating-point absolute value function
#include <math.h>
double fabs (double x)
float fabs (float x)
The fabs(3) and fabsf(3) functions compute the absolute value of a floating-point number x.
The fabs(3) call takes and returns a double, while fabsf(3) takes and returns a float.
The fabs(3) and fabsf(3) functions return the absolute value of x.
abs(3)
ceil(3)
floor(3)