NAME

isgreater, isgreaterequal, isless, islessequal, islessgreater, isunordered - macros to test a relation

SYNOPSIS

#include <math.h>

int isgreater(x,y);

int isgreaterequal(x,y);

int isless(x,y);

int islessequal(x,y);

int islessgreater(x,y);

int isunordered(x,y);

Compile with -std=c99; link with -lm.

DESCRIPTION

The normal relation operations (like less) will fail if one of the operands is NaN. This will cause an exception. To avoid this, C99 defines these macros. The macros are guaranteed to evaluate their operands only once. The operand can be of any real floating-point type.

isgreater()

determines (x) > (y) without an exception if x or y is NaN.

isgreaterequal()

determines (x) >= (y) without an exception if x or y is NaN.

isless()

determines (x) < (y) without an exception if x or y is NaN.

islessequal()

determines (x) <= (y) without an exception if x or y is NaN.

islessgreater()

determines (x) < (y) || (x) > (y) without an exception if x or y is NaN. This macro is not equivalent to x != y because that expression is true if x or y is NaN.

isunordered()

is true if x or y is NaN and false otherwise.

CONFORMING TO

C99

NOTES

Not all hardware supports these functions, and where it doesn't, they will be emulated by macros. This will give you a performance penalty. Don't use these functions if NaN is of no concern for you.

SEE ALSO

fpclassify(3), isnan(3)

COLOPHON

This page is part of release 3.02 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.