fmax, fmaxf, fmaxl — 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);

Link with -lm.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

fmax(), fmaxf(), fmaxl():



These functions return the larger value of x and y.

Return Value

These functions return the maximum of x and y.

If one argument is a NaN, the other argument is returned.

If both arguments are NaN, a NaN is returned.


No errors occur.


These functions first appeared in glibc in version 2.1.


For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
fmax(), fmaxf(), fmaxl() Thread safety MT-Safe

Conforming to

C99, POSIX.1-2001, POSIX.1-2008.

See Also

fdim(3), fmin(3)


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Referenced By

fdim(3), fmin(3).

The man pages fmaxf(3) and fmaxl(3) are aliases of fmax(3).

2017-09-15 Linux Programmer's Manual