fmaxf
(3)determine maximum of two floating-point numbers
#include <math.h> double fmax(double x, double y); float fmaxf(float x, float y); long double fmaxl(long double x, long double y); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): fmax(), fmaxf(), fmaxl(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L