std::fmax, std::fmaxf, std::fmaxl

Defined in header <cmath>
float       fmax ( float x, float y );
float       fmaxf( float x, float y );
(1) (since C++11)
double      fmax ( double x, double y );
(2) (since C++11)
long double fmax ( long double x, long double y );
long double fmaxl( long double x, long double y );
(3) (since C++11)
Promoted    fmax ( Arithmetic1 x, Arithmetic2 y );
(4) (since C++11)
1-3) Returns the larger of two floating point arguments, treating NaNs as missing data (between a NaN and a numeric value, the numeric value is chosen)
4) A set of overloads or a function template for all combinations of arguments of arithmetic type not covered by 1-3). If any argument has integral type, it is cast to double. If any other argument is long double, then the return type is long double, otherwise it is double.


x, y - values of floating-point or integral types

Return value

If successful, returns the larger of two floating point values. The value returned is exact and does not depend on any rounding modes.

Error handling

This function is not subject to any of the error conditions specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

  • If one of the two arguments is NaN, the value of the other argument is returned
  • Only if both arguments are NaN, NaN is returned


This function is not required to be sensitive to the sign of zero, although some implementations additionally enforce that if one argument is +0 and the other is -0, then +0 is returned.


#include <iostream>
#include <cmath>
int main()
    std::cout << "fmax(2,1)    = " << std::fmax(2,1) << '\n'
              << "fmax(-Inf,0) = " << std::fmax(-INFINITY,0) << '\n'
              << "fmax(NaN,-1) = " << std::fmax(NAN,-1) << '\n';


fmax(2,1)    = 2
fmax(-Inf,0) = 0
fmax(NaN,-1) = -1

See also

checks if the first floating-point argument is greater than the second
smaller of two floating point values
returns the greater of the given values
(function template)
returns the largest element in a range
(function template)
returns the smaller and larger of two elements
(function template)
returns the smallest and the largest elements in a range
(function template)

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.