ISGREATER
Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
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NAME
isgreater, isgreaterequal, isless, islessequal, islessgreater,
isunordered - floating-point relational tests without exception for NaN
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);
Link with -lm.
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
All functions described here:
-
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
DESCRIPTION
The normal relational operations (like
<,
"less than")
will fail if one of the operands is NaN.
This will cause an exception.
To avoid this, C99 defines the macros listed below.
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
not
be promoted to real-floating types).
- 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()
-
determines whether its arguments are unordered, that is, whether
at least one of the arguments is a NaN.
RETURN VALUE
The macros other than
isunordered()
return the result of the relational comparison;
these macros return 0 if either argument is a NaN.
isunordered()
returns 1 if
x
or
y
is NaN and 0 otherwise.
ERRORS
No errors occur.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
|
isgreater(),
isgreaterequal(),
isless(),
islessequal(),
islessgreater(),
isunordered()
| Thread safety | MT-Safe
|
CONFORMING TO
POSIX.1-2001, POSIX.1-2008, C99.
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.
SEE ALSO
fpclassify(3),
isnan(3)
COLOPHON
This page is part of release 4.13 of the Linux
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/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
- COLOPHON
-
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|
- Running on 
-
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