1ISGREATER(3)               Linux Programmer's Manual              ISGREATER(3)
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NAME

6       isgreater,    isgreaterequal,   isless,   islessequal,   islessgreater,
7       isunordered - floating-point relational tests without exception for NaN
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SYNOPSIS

10       #include <math.h>
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12       int isgreater(x, y);
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14       int isgreaterequal(x, y);
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16       int isless(x, y);
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18       int islessequal(x, y);
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20       int islessgreater(x, y);
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22       int isunordered(x, y);
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24       Link with -lm.
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26   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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28       All functions described here:
29              _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
30              _POSIX_C_SOURCE >= 200112L;
31              or cc -std=c99
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DESCRIPTION

34       The  normal  relation operations (like <, "less than") will fail if one
35       of the operands is NaN.  This will cause an exception.  To avoid  this,
36       C99 defines the macros listed below.
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38       These macros are guaranteed to evaluate their arguments only once.  The
39       arguments must be of real floating-point type (note: do not pass  inte‐
40       ger  values  as arguments to these macros, since the arguments will not
41       be promoted to real-floating types).
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43       isgreater()
44              determines (x) > (y) without an exception if x or y is NaN.
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46       isgreaterequal()
47              determines (x) >= (y) without an exception if x or y is NaN.
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49       isless()
50              determines (x) < (y) without an exception if x or y is NaN.
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52       islessequal()
53              determines (x) <= (y) without an exception if x or y is NaN.
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55       islessgreater()
56              determines (x) < (y) || (x) > (y) without an exception if x or y
57              is  NaN.   This  macro  is not equivalent to x != y because that
58              expression is true if x or y is NaN.
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60       isunordered()
61              determines whether its arguments are unordered, that is, whether
62              at least one of the arguments is a NaN.
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RETURN VALUE

65       The macros other than isunordered() return the result of the relational
66       comparison; these macros return 0 if either argument is a NaN.
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68       isunordered() returns 1 if x or y is NaN and 0 otherwise.
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ERRORS

71       No errors occur.
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CONFORMING TO

74       C99, POSIX.1-2001.
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NOTES

77       Not all hardware supports these functions, and where  hardware  support
78       isn't provided, they will be emulated by macros.  This will result in a
79       performance penalty.  Don't use these functions if NaN is of no concern
80       for you.
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SEE ALSO

83       fpclassify(3), isnan(3)
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COLOPHON

86       This  page  is  part of release 3.53 of the Linux man-pages project.  A
87       description of the project, and information about reporting  bugs,  can
88       be found at http://www.kernel.org/doc/man-pages/.
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92                                  2012-05-06                      ISGREATER(3)
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