man3/remainder.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  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  2003-11-18 "" "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 .SH DESCRIPTION
  54 The
  55 .BR remainder ()
  56 function computes the remainder of dividing
  57 .I x
  58 by
  59 .IR y .
  60 The return value is
  61 .IR x " \- " n " * " y ,
  62 where
  63 .I n
  64 is the value
  65 .IR x " / " y ,
  66 rounded to the nearest integer.
  67 If this quotient is 1/2 (mod 1), it is rounded to the nearest even number
  68 (independent of the current rounding mode).
  69 If the return value is 0, it has the sign of
  70 .IR x .
  71 .LP
  72 The
  73 .BR drem ()
  74 function does precisely the same thing.
  75 .SH "RETURN VALUE"
  76 The
  77 .BR remainder ()
  78 function returns the remainder, unless
  79 .I y
  80 is zero, when the function fails and
  81 .I errno
  82 is set.
  83 .SH ERRORS
  84 .TP
  85 .B EDOM
  86 The denominator
  87 .I y
  88 is zero.
  89 .SH "CONFORMING TO"
  90 IEC 60559.
  91 The functions
  92 .BR remainder (),
  93 .BR remainderf (),
  94 and
  95 .BR remainderl ()
  96 are from C99.
  97 The function
  98 .BR drem ()
  99 is from 4.3BSD.
 100 The
 101 .I float
 102 and
 103 .I "long double"
 104 variants
 105 .BR dremf ()
 106 and
 107 .BR dreml ()
 108 exist on some systems, such as Tru64 and glibc2.
 109 .SH EXAMPLE
 110 The call "remainder(29.0, 3.0)" returns \-1.
 111 .SH "SEE ALSO"
 112 .BR fmod (3),
 113 .BR remquo (3)