man3/fmod.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
   2 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
   3 .\"     <mtk.manpages@gmail.com>
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  27 .\" References consulted:
  28 .\"     Linux libc source code
  29 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  30 .\"     386BSD man pages
  31 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
  32 .\" Modified 2002-07-27 by Walter Harms
  33 .\"     (walter.harms@informatik.uni-oldenburg.de)
  34 .\"
  35 .TH FMOD 3  2017-09-15 "" "Linux Programmer's Manual"
  36 .SH NAME
  37 fmod, fmodf, fmodl \- floating-point remainder function
  38 .SH SYNOPSIS
  39 .nf
  40 .B #include <math.h>
  41 .PP
  42 .BI "double fmod(double " x ", double " y );
  43 .BI "float fmodf(float " x ", float " y );
  44 .BI "long double fmodl(long double " x ", long double " y );
  45 .fi
  46 .PP
  47 Link with \fI\-lm\fP.
  48 .PP
  49 .in -4n
  50 Feature Test Macro Requirements for glibc (see
  51 .BR feature_test_macros (7)):
  52 .in
  53 .PP
  54 .ad l
  55 .BR fmodf (),
  56 .BR fmodl ():
  57 .RS 4
  58 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  59     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  60     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  61 .RE
  62 .ad
  63 .SH DESCRIPTION
  64 These functions compute the floating-point remainder of dividing
  65 .I x
  66 by
  67 .IR y .
  68 The return value is
  69 .IR x
  70 \-
  71 .I n
  72 *
  73 .IR y ,
  74 where
  75 .I n
  76 is the quotient of
  77 .I x
  78 /
  79 .IR y ,
  80 rounded toward zero to an integer.
  81 .SH RETURN VALUE
  82 On success, these
  83 functions return the value \fIx\fP\ \-\ \fIn\fP*\fIy\fP,
  84 for some integer
  85 .IR n ,
  86 such that the returned value has the same sign as
  87 .I x
  88 and a magnitude less than the magnitude of
  89 .IR y .
  90 .PP
  91 If
  92 .I x
  93 or
  94 .I y
  95 is a NaN, a NaN is returned.
  96 .PP
  97 If
  98 .I x
  99 is an infinity,
 100 a domain error occurs, and
 101 a NaN is returned.
 102 .PP
 103 If
 104 .I y
 105 is zero,
 106 a domain error occurs, and
 107 a NaN is returned.
 108 .PP
 109 If
 110 .I x
 111 is +0 (\-0), and
 112 .I y
 113 is not zero, +0 (\-0) is returned.
 114 .SH ERRORS
 115 See
 116 .BR math_error (7)
 117 for information on how to determine whether an error has occurred
 118 when calling these functions.
 119 .PP
 120 The following errors can occur:
 121 .TP
 122 Domain error: \fIx\fP is an infinity
 123 .I errno
 124 is set to
 125 .BR EDOM
 126 (but see BUGS).
 127 An invalid floating-point exception
 128 .RB ( FE_INVALID )
 129 is raised.
 130 .TP
 131 Domain error: \fIy\fP is zero
 132 .I errno
 133 is set to
 134 .BR EDOM .
 135 An invalid floating-point exception
 136 .RB ( FE_INVALID )
 137 is raised.
 138 .\" POSIX.1 documents an optional underflow error, but AFAICT it doesn't
 139 .\" (can't?) occur -- mtk, Jul 2008
 140 .SH ATTRIBUTES
 141 For an explanation of the terms used in this section, see
 142 .BR attributes (7).
 143 .TS
 144 allbox;
 145 lbw24 lb lb
 146 l l l.
 147 Interface       Attribute       Value
 148 T{
 149 .BR fmod (),
 150 .BR fmodf (),
 151 .BR fmodl ()
 152 T}      Thread safety   MT-Safe
 153 .TE
 154 .SH CONFORMING TO
 155 C99, POSIX.1-2001, POSIX.1-2008.
 156 .PP
 157 The variant returning
 158 .I double
 159 also conforms to
 160 SVr4, 4.3BSD, C89.
 161 .SH BUGS
 162 Before version 2.10, the glibc implementation did not set
 163 .\" http://sources.redhat.com/bugzilla/show_bug.cgi?id=6784
 164 .I errno
 165 to
 166 .B EDOM
 167 when a domain error occurred for an infinite
 168 .IR x .
 169 .SH SEE ALSO
 170 .BR remainder (3)