7.12.14.3 The isless macro
Synopsis
#include <math.h>
int isless(real-floating x, real-floating y);
Description
The isless macro determines whether its first argument is less than its second argument. The value of isless(x, y) is always equal to (x) < (y); however, unlike (x) < (y), isless(x, y) does not raise the “invalid” floating-point exception when x and y are unordered.
Returns
The isless macro returns the value of (x) < (y).