man3/fdim.3

   1 '\" t
   2 .\" Copyright 2003 Walter Harms, Andries Brouwer
   3 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
   4 .\"     <mtk.manpages@gmail.com>
   5 .\"
   6 .\" SPDX-License-Identifier: GPL-1.0-or-later
   7 .\"
   8 .TH fdim 3 (date) "Linux man-pages (unreleased)"
   9 .SH NAME
  10 fdim, fdimf, fdiml \- positive difference
  11 .SH LIBRARY
  12 Math library
  13 .RI ( libm ", " \-lm )
  14 .SH SYNOPSIS
  15 .nf
  16 .B #include <math.h>
  17 .PP
  18 .BI "double fdim(double " x ", double " y );
  19 .BI "float fdimf(float " x ", float " y );
  20 .BI "long double fdiml(long double " x ", long double " y );
  21 .fi
  22 .PP
  23 .RS -4
  24 Feature Test Macro Requirements for glibc (see
  25 .BR feature_test_macros (7)):
  26 .RE
  27 .PP
  28 .BR fdimf (),
  29 .BR fdiml ():
  30 .nf
  31     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  32 .fi
  33 .SH DESCRIPTION
  34 These functions return the positive difference, max(\fIx\fP-\fIy\fP,0),
  35 between their arguments.
  36 .SH RETURN VALUE
  37 On success, these functions return the positive difference.
  38 .PP
  39 If
  40 .I x
  41 or
  42 .I y
  43 is a NaN, a NaN is returned.
  44 .PP
  45 If the result overflows,
  46 a range error occurs,
  47 and the functions return
  48 .BR HUGE_VAL ,
  49 .BR HUGE_VALF ,
  50 or
  51 .BR HUGE_VALL ,
  52 respectively.
  53 .SH ERRORS
  54 See
  55 .BR math_error (7)
  56 for information on how to determine whether an error has occurred
  57 when calling these functions.
  58 .PP
  59 The following errors can occur:
  60 .TP
  61 Range error: result overflow
  62 .I errno
  63 is set to
  64 .BR ERANGE .
  65 An overflow floating-point exception
  66 .RB ( FE_OVERFLOW )
  67 is raised.
  68 .SH ATTRIBUTES
  69 For an explanation of the terms used in this section, see
  70 .BR attributes (7).
  71 .ad l
  72 .nh
  73 .TS
  74 allbox;
  75 lbx lb lb
  76 l l l.
  77 Interface       Attribute       Value
  78 T{
  79 .BR fdim (),
  80 .BR fdimf (),
  81 .BR fdiml ()
  82 T}      Thread safety   MT-Safe
  83 .TE
  84 .hy
  85 .ad
  86 .sp 1
  87 .SH STANDARDS
  88 C11, POSIX.1-2008.
  89 .SH HISTORY
  90 glibc 2.1.
  91 C99, POSIX.1-2001.
  92 .SH BUGS
  93 Before glibc 2.24
  94 .\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6796
  95 on certain architectures (e.g., x86, but not x86_64)
  96 these functions did not set
  97 .IR errno .
  98 .SH SEE ALSO
  99 .BR fmax (3)