man3/sqrt.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
   2 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
   3 .\"     <mtk.manpages@gmail.com>
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  27 .\" References consulted:
  28 .\"     Linux libc source code
  29 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  30 .\"     386BSD man pages
  31 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
  32 .\" Modified 2002-07-27 by Walter Harms
  33 .\"     (walter.harms@informatik.uni-oldenburg.de)
  34 .TH SQRT 3  2017-09-15 ""  "Linux Programmer's Manual"
  35 .SH NAME
  36 sqrt, sqrtf, sqrtl \- square root function
  37 .SH SYNOPSIS
  38 .nf
  39 .B #include <math.h>
  40 .PP
  41 .BI "double sqrt(double " x );
  42 .BI "float sqrtf(float " x );
  43 .BI "long double sqrtl(long double " x );
  44 .fi
  45 .PP
  46 Link with \fI\-lm\fP.
  47 .PP
  48 .in -4n
  49 Feature Test Macro Requirements for glibc (see
  50 .BR feature_test_macros (7)):
  51 .in
  52 .PP
  53 .ad l
  54 .BR sqrtf (),
  55 .BR sqrtl ():
  56 .RS 4
  57 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  58     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  59     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  60 .RE
  61 .ad
  62 .SH DESCRIPTION
  63 These functions return the nonnegative square root of
  64 .IR x .
  65 .SH RETURN VALUE
  66 On success, these functions return the square root of
  67 .IR x .
  68 .PP
  69 If
  70 .I x
  71 is a NaN, a NaN is returned.
  72 .PP
  73 If
  74 .I x
  75 is +0 (\-0), +0 (\-0) is returned.
  76 .PP
  77 If
  78 .I x
  79 is positive infinity, positive infinity is returned.
  80 .PP
  81 If
  82 .I x
  83 is less than \-0,
  84 a domain error occurs,
  85 and a NaN is returned.
  86 .SH ERRORS
  87 See
  88 .BR math_error (7)
  89 for information on how to determine whether an error has occurred
  90 when calling these functions.
  91 .PP
  92 The following errors can occur:
  93 .TP
  94 Domain error: \fIx\fP less than \-0
  95 .I errno
  96 is set to
  97 .BR EDOM .
  98 An invalid floating-point exception
  99 .RB ( FE_INVALID )
 100 is raised.
 101 .SH ATTRIBUTES
 102 For an explanation of the terms used in this section, see
 103 .BR attributes (7).
 104 .TS
 105 allbox;
 106 lbw24 lb lb
 107 l l l.
 108 Interface       Attribute       Value
 109 T{
 110 .BR sqrt (),
 111 .BR sqrtf (),
 112 .BR sqrtl ()
 113 T}      Thread safety   MT-Safe
 114 .TE
 115 .SH CONFORMING TO
 116 C99, POSIX.1-2001, POSIX.1-2008.
 117 .PP
 118 The variant returning
 119 .I double
 120 also conforms to
 121 SVr4, 4.3BSD, C89.
 122 .SH SEE ALSO
 123 .BR cbrt (3),
 124 .BR csqrt (3),
 125 .BR hypot (3)