man3/fabs.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  25 .\" References consulted:
  26 .\"     Linux libc source code
  27 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  28 .\"     386BSD man pages
  29 .\" Modified Sat Jul 24 19:42:04 1993 by Rik Faith (faith@cs.unc.edu)
  30 .\" Added fabsl, fabsf, aeb, 2001-06-07
  31 .\"
  32 .TH FABS 3  2017-09-15 "" "Linux Programmer's Manual"
  33 .SH NAME
  34 fabs, fabsf, fabsl \- absolute value of floating-point number
  35 .SH SYNOPSIS
  36 .nf
  37 .B #include <math.h>
  38 .PP
  39 .BI "double fabs(double " x );
  40 .BI "float fabsf(float " x );
  41 .BI "long double fabsl(long double " x );
  42 .fi
  43 .PP
  44 Link with \fI\-lm\fP.
  45 .PP
  46 .in -4n
  47 Feature Test Macro Requirements for glibc (see
  48 .BR feature_test_macros (7)):
  49 .in
  50 .PP
  51 .ad l
  52 .BR fabsf (),
  53 .BR fabsl ():
  54 .RS 4
  55 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  56     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  57     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  58 .RE
  59 .ad b
  60 .SH DESCRIPTION
  61 These functions return the absolute value of the floating-point
  62 number
  63 .IR x .
  64 .SH RETURN VALUE
  65 These functions return the absolute value of
  66 .IR x .
  67 .PP
  68 If
  69 .I x
  70 is a NaN, a NaN is returned.
  71 .PP
  72 If
  73 .I x
  74 is \-0, +0 is returned.
  75 .PP
  76 If
  77 .I x
  78 is negative infinity or positive infinity, positive infinity is returned.
  79 .SH ERRORS
  80 No errors occur.
  81 .SH ATTRIBUTES
  82 For an explanation of the terms used in this section, see
  83 .BR attributes (7).
  84 .TS
  85 allbox;
  86 lbw24 lb lb
  87 l l l.
  88 Interface       Attribute       Value
  89 T{
  90 .BR fabs (),
  91 .BR fabsf (),
  92 .BR fabsl ()
  93 T}      Thread safety   MT-Safe
  94 .TE
  95 .SH CONFORMING TO
  96 C99, POSIX.1-2001, POSIX.1-2008.
  97 .PP
  98 The variant returning
  99 .I double
 100 also conforms to
 101 SVr4, 4.3BSD, C89.
 102 .SH SEE ALSO
 103 .BR abs (3),
 104 .BR cabs (3),
 105 .BR ceil (3),
 106 .BR floor (3),
 107 .BR labs (3),
 108 .BR rint (3)