F.9.9.2 The fmax functions

1

If just one argument is a NaN, the fmax functions return the other argument (if both arguments are NaNs, the functions return a NaN).

2

The body of the fmax function might be[1]

{ return (isgreaterequal(x, y) ||
     isnan(y)) ? x : y; }

Footnotes

[1]

Ideally, fmax would be sensitive to the sign of zero, for example fmax(-0.0, +0.0) would return +0; however, implementation in software might be impractical.