man3/isgreater.3

   1 '\" t
   2 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
   3 .\"
   4 .\" SPDX-License-Identifier: GPL-1.0-or-later
   5 .\"
   6 .\" 2002-07-27 Walter Harms
   7 .\" this was done with the help of the glibc manual
   8 .\"
   9 .TH isgreater 3 (date) "Linux man-pages (unreleased)"
  10 .SH NAME
  11 isgreater, isgreaterequal, isless, islessequal, islessgreater,
  12 isunordered \- floating-point relational tests without exception for NaN
  13 .SH LIBRARY
  14 Math library
  15 .RI ( libm ", " \-lm )
  16 .SH SYNOPSIS
  17 .nf
  18 .B #include <math.h>
  19 .PP
  20 .BI "int isgreater(" x ", " y );
  21 .BI "int isgreaterequal(" x ", " y );
  22 .BI "int isless(" x ", " y );
  23 .BI "int islessequal(" x ", " y );
  24 .BI "int islessgreater(" x ", " y );
  25 .BI "int isunordered(" x ", " y );
  26 .fi
  27 .PP
  28 .RS -4
  29 Feature Test Macro Requirements for glibc (see
  30 .BR feature_test_macros (7)):
  31 .RE
  32 .PP
  33 .nf
  34     All functions described here:
  35         _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  36 .fi
  37 .SH DESCRIPTION
  38 The normal relational operations (like
  39 .BR < ,
  40 "less than")
  41 fail if one of the operands is NaN.
  42 This will cause an exception.
  43 To avoid this, C99 defines the macros listed below.
  44 .PP
  45 These macros are guaranteed to evaluate their arguments only once.
  46 The arguments must be of real floating-point type (note: do not pass
  47 integer values as arguments to these macros, since the arguments will
  48 .I not
  49 be promoted to real-floating types).
  50 .TP
  51 .BR isgreater ()
  52 determines \fI(x)\ >\ (y)\fP without an exception
  53 if
  54 .I x
  55 or
  56 .I y
  57 is NaN.
  58 .TP
  59 .BR isgreaterequal ()
  60 determines \fI(x)\ >=\ (y)\fP without an exception
  61 if
  62 .I x
  63 or
  64 .I y
  65 is NaN.
  66 .TP
  67 .BR isless ()
  68 determines \fI(x)\ <\ (y)\fP without an exception
  69 if
  70 .I x
  71 or
  72 .I y
  73 is NaN.
  74 .TP
  75 .BR islessequal ()
  76 determines \fI(x)\ <=\ (y)\fP without an exception
  77 if
  78 .I x
  79 or
  80 .I y
  81 is NaN.
  82 .TP
  83 .BR islessgreater ()
  84 determines \fI(x)\ < (y) || (x) >\ (y)\fP
  85 without an exception if
  86 .I x
  87 or
  88 .I y
  89 is NaN.
  90 This macro is not equivalent to \fIx\ !=\ y\fP because that expression is
  91 true if
  92 .I x
  93 or
  94 .I y
  95 is NaN.
  96 .TP
  97 .BR isunordered ()
  98 determines whether its arguments are unordered, that is, whether
  99 at least one of the arguments is a NaN.
 100 .SH RETURN VALUE
 101 The macros other than
 102 .BR isunordered ()
 103 return the result of the relational comparison;
 104 these macros return 0 if either argument is a NaN.
 105 .PP
 106 .BR isunordered ()
 107 returns 1 if
 108 .I x
 109 or
 110 .I y
 111 is NaN and 0 otherwise.
 112 .SH ERRORS
 113 No errors occur.
 114 .SH ATTRIBUTES
 115 For an explanation of the terms used in this section, see
 116 .BR attributes (7).
 117 .TS
 118 allbox;
 119 lbx lb lb
 120 l l l.
 121 Interface       Attribute       Value
 122 T{
 123 .na
 124 .nh
 125 .BR isgreater (),
 126 .BR isgreaterequal (),
 127 .BR isless (),
 128 .BR islessequal (),
 129 .BR islessgreater (),
 130 .BR isunordered ()
 131 T}      Thread safety   MT-Safe
 132 .TE
 133 .sp 1
 134 .SH VERSIONS
 135 Not all hardware supports these functions,
 136 and where hardware support isn't provided, they will be emulated by macros.
 137 This will result in a performance penalty.
 138 Don't use these functions if NaN is of no concern for you.
 139 .SH STANDARDS
 140 C11, POSIX.1-2008.
 141 .SH HISTORY
 142 POSIX.1-2001, C99.
 143 .SH SEE ALSO
 144 .BR fpclassify (3),
 145 .BR isnan (3)