.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)

.\"

.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)

.\" Distributed under GPL

.\" %%%LICENSE_END

.\"

.\" 2002-07-27 Walter Harms

.\" this was done with the help of the glibc manual

.\"

.TH ISGREATER 3  2017-09-15 "" "Linux Programmer's Manual"

.SH NAME

isgreater, isgreaterequal, isless, islessequal, islessgreater,

isunordered \- floating-point relational tests without exception for NaN

.SH SYNOPSIS

.nf

.B #include <math.h>

.PP

.BI "int isgreater(" x ", " y );

.PP

.BI "int isgreaterequal(" x ", " y );

.PP

.BI "int isless(" x ", " y );

.PP

.BI "int islessequal(" x ", " y );

.PP

.BI "int islessgreater(" x ", " y );

.PP

.BI "int isunordered(" x ", " y );

.fi

.PP

Link with \fI\-lm\fP.

.PP

.in -4n

Feature Test Macro Requirements for glibc (see

.BR feature_test_macros (7)):

.in

.PP

.ad l

All functions described here:

.RS

_ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L

.RE

.ad b

.SH DESCRIPTION

The normal relational operations (like

.BR < ,

"less than")

fail if one of the operands is NaN.

This will cause an exception.

To avoid this, C99 defines the macros listed below.

.PP

These macros are guaranteed to evaluate their arguments only once.

The arguments must be of real floating-point type (note: do not pass

integer values as arguments to these macros, since the arguments will

.I not

be promoted to real-floating types).

.TP

.BR isgreater ()

determines \fI(x)\ >\ (y)\fP without an exception

if

.IR x

or

.I y

is NaN.

.TP

.BR isgreaterequal ()

determines \fI(x)\ >=\ (y)\fP without an exception

if

.IR x

or

.I y

is NaN.

.TP

.BR isless ()

determines \fI(x)\ <\ (y)\fP without an exception

if

.IR x

or

.I y

is NaN.

.TP

.BR islessequal ()

determines \fI(x)\ <=\ (y)\fP without an exception

if

.IR x

or

.I y

is NaN.

.TP

.BR islessgreater ()

determines \fI(x)\ < (y) || (x) >\ (y)\fP

without an exception if

.IR x

or

.I y

is NaN.

This macro is not equivalent to \fIx\ !=\ y\fP because that expression is

true if

.IR x

or

.I y

is NaN.

.TP

.BR isunordered ()

determines whether its arguments are unordered, that is, whether

at least one of the arguments is a NaN.

.SH RETURN VALUE

The macros other than

.BR isunordered ()

return the result of the relational comparison;

these macros return 0 if either argument is a NaN.

.PP

.BR isunordered ()

returns 1 if

.IR x

or

.I y

is NaN and 0 otherwise.

.SH ERRORS

No errors occur.

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.ad l

.TS

allbox;

lbw30 lb lb

l l l.

Interface	Attribute	Value

T{

.BR isgreater (),

.BR isgreaterequal (),

.BR isless (),

.BR islessequal (),

.BR islessgreater (),

.BR isunordered ()

T}	Thread safety	MT-Safe

.TE

.ad

.SH CONFORMING TO

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

.SH NOTES

Not all hardware supports these functions,

and where hardware support isn't provided, they will be emulated by macros.

This will result in a performance penalty.

Don't use these functions if NaN is of no concern for you.

.SH SEE ALSO

.BR fpclassify (3),

.BR isnan (3)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.