man3/fdim.3

   1 .\" Copyright 2003 Walter Harms, Andries Brouwer
   2 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
   3 .\"     <mtk.manpages@gmail.com>
   4 .\"
   5 .\" SPDX-License-Identifier: GPL-1.0-or-later
   6 .\"
   7 .TH FDIM 3 2021-03-22 "" "Linux Programmer's Manual"
   8 .SH NAME
   9 fdim, fdimf, fdiml \- positive difference
  10 .SH LIBRARY
  11 Math library
  12 .RI ( libm ", " \-lm )
  13 .SH SYNOPSIS
  14 .nf
  15 .B #include <math.h>
  16 .PP
  17 .BI "double fdim(double " x ", double " y );
  18 .BI "float fdimf(float " x ", float " y );
  19 .BI "long double fdiml(long double " x ", long double " y );
  20 .fi
  21 .PP
  22 .RS -4
  23 Feature Test Macro Requirements for glibc (see
  24 .BR feature_test_macros (7)):
  25 .RE
  26 .PP
  27 .BR fdimf (),
  28 .BR fdiml ():
  29 .nf
  30     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  31 .fi
  32 .SH DESCRIPTION
  33 These functions return the positive difference, max(\fIx\fP-\fIy\fP,0),
  34 between their arguments.
  35 .SH RETURN VALUE
  36 On success, these functions return the positive difference.
  37 .PP
  38 If
  39 .I x
  40 or
  41 .I y
  42 is a NaN, a NaN is returned.
  43 .PP
  44 If the result overflows,
  45 a range error occurs,
  46 and the functions return
  47 .BR HUGE_VAL ,
  48 .BR HUGE_VALF ,
  49 or
  50 .BR HUGE_VALL ,
  51 respectively.
  52 .SH ERRORS
  53 See
  54 .BR math_error (7)
  55 for information on how to determine whether an error has occurred
  56 when calling these functions.
  57 .PP
  58 The following errors can occur:
  59 .TP
  60 Range error: result overflow
  61 .I errno
  62 is set to
  63 .BR ERANGE .
  64 An overflow floating-point exception
  65 .RB ( FE_OVERFLOW )
  66 is raised.
  67 .SH VERSIONS
  68 These functions first appeared in glibc in version 2.1.
  69 .SH ATTRIBUTES
  70 For an explanation of the terms used in this section, see
  71 .BR attributes (7).
  72 .ad l
  73 .nh
  74 .TS
  75 allbox;
  76 lbx lb lb
  77 l l l.
  78 Interface       Attribute       Value
  79 T{
  80 .BR fdim (),
  81 .BR fdimf (),
  82 .BR fdiml ()
  83 T}      Thread safety   MT-Safe
  84 .TE
  85 .hy
  86 .ad
  87 .sp 1
  88 .SH CONFORMING TO
  89 C99, POSIX.1-2001, POSIX.1-2008.
  90 .SH BUGS
  91 Before glibc version 2.24
  92 .\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6796
  93 on certain architectures (e.g., x86, but not x86_64)
  94 these functions did not set
  95 .IR errno .
  96 .SH SEE ALSO
  97 .BR fmax (3)