fmax(), fmaxf(), fmaxl()

Updated: October 26, 2022

Determine the 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 );


x, y
The numbers that you want to compare.


The general-purpose math library.
(QNX Neutrino 7.1 or later) A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.

Your system requirements will determine how you should work with these libraries:

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.


The fmax(), fmaxf(), and fmaxl() functions determine the maximum of two floating-point numbers.

To check for error situations, use feclearexcept() and fetestexcept(). For example:


The maximum of the arguments.

If: These functions return: Errors:
x and y are both NaN NaN
Just one of the arguments is NaN The numeric value

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.


C11, POSIX 1003.1

Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes