man3/remainder.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  12 .\" Since the Linux kernel and libraries are constantly changing, this
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  22 .\"
  23 .\" References consulted:
  24 .\"     Linux libc source code
  25 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  26 .\"     386BSD man pages
  27 .\"
  28 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
  29 .\" Modified 2002-08-10 Walter Harms
  30 .\"     (walter.harms@informatik.uni-oldenburg.de)
  31 .\" Modified 2003-11-18, 2004-10-05 aeb
  32 .\"
  33 .TH REMAINDER 3  2007-07-26 "" "Linux Programmer's Manual"
  34 .SH NAME
  35 drem, dremf, dreml, remainder, remainderf, remainderl \- \
  36 floating-point remainder function
  37 .SH SYNOPSIS
  38 .nf
  39 .B #include <math.h>
  40 .sp
  41 /* The C99 versions */
  42 .BI "double remainder(double " x ", double " y );
  43 .BI "float remainderf(float " x ", float " y );
  44 .BI "long double remainderl(long double " x ", long double " y );
  45 .sp
  46 /* Obsolete synonyms */
  47 .BI "double drem(double " x ", double " y );
  48 .BI "float dremf(float " x ", float " y );
  49 .BI "long double dreml(long double " x ", long double " y );
  50 .sp
  51 .fi
  52 Link with \fI\-lm\fP.
  53 .sp
  54 .in -4n
  55 Feature Test Macro Requirements for glibc (see
  56 .BR feature_test_macros (7)):
  57 .in
  58 .sp
  59 .ad l
  60 .BR remainder (),
  61 .BR remainderf (),
  62 .BR remainderl ():
  63 _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 || _ISOC99_SOURCE; or
  64 .I cc\ -std=c99
  65 .br
  66 .BR drem (),
  67 .BR dremf (),
  68 .BR dreml ():
  69 _SVID_SOURCE || _BSD_SOURCE
  70 .ad b
  71 .SH DESCRIPTION
  72 The
  73 .BR remainder ()
  74 function computes the remainder of dividing
  75 .I x
  76 by
  77 .IR y .
  78 The return value is
  79 .IR x " \- " n " * " y ,
  80 where
  81 .I n
  82 is the value
  83 .IR x " / " y ,
  84 rounded to the nearest integer.
  85 If this quotient is 1/2 (mod 1), it is rounded to the nearest even number
  86 (independent of the current rounding mode).
  87 If the return value is 0, it has the sign of
  88 .IR x .
  89 .LP
  90 The
  91 .BR drem ()
  92 function does precisely the same thing.
  93 .SH "RETURN VALUE"
  94 The
  95 .BR remainder ()
  96 function returns the remainder, unless
  97 .I y
  98 is zero, when the function fails and
  99 .I errno
 100 is set.
 101 .SH ERRORS
 102 .TP
 103 .B EDOM
 104 The denominator
 105 .I y
 106 is zero.
 107 .SH "CONFORMING TO"
 108 IEC 60559.
 109 The functions
 110 .BR remainder (),
 111 .BR remainderf (),
 112 and
 113 .BR remainderl ()
 114 are from C99.
 115 The function
 116 .BR drem ()
 117 is from 4.3BSD.
 118 The
 119 .I float
 120 and
 121 .I "long double"
 122 variants
 123 .BR dremf ()
 124 and
 125 .BR dreml ()
 126 exist on some systems, such as Tru64 and glibc2.
 127 .SH EXAMPLE
 128 The call "remainder(29.0, 3.0)" returns \-1.
 129 .SH "SEE ALSO"
 130 .BR fmod (3),
 131 .BR remquo (3)