double abs (double x); float abs (float x); long double abs (long double x);
double abs (double x); float abs (float x); long double abs (long double x); double abs (T x); // additional overloads for integral types
double abs (double x); float abs (float x); long double abs (long double x);
double abs (double x); float abs (float x); long double abs (long double x); double abs (T x); // additional overloads for integral types