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  2016-03-15 ""  "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 .br
  43 .BI "float sqrtf(float " x );
  44 .br
  45 .BI "long double sqrtl(long double " x );
  46 .fi
  47 .PP
  48 Link with \fI\-lm\fP.
  49 .PP
  50 .in -4n
  51 Feature Test Macro Requirements for glibc (see
  52 .BR feature_test_macros (7)):
  53 .in
  54 .PP
  55 .ad l
  56 .BR sqrtf (),
  57 .BR sqrtl ():
  58 .RS 4
  59 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  60     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  61     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  62 .RE
  63 .ad
  64 .SH DESCRIPTION
  65 These functions return the nonnegative square root of
  66 .IR x .
  67 .SH RETURN VALUE
  68 On success, these functions return the square root of
  69 .IR x .
  70
  71 If
  72 .I x
  73 is a NaN, a NaN is returned.
  74
  75 If
  76 .I x
  77 is +0 (\-0), +0 (\-0) is returned.
  78
  79 If
  80 .I x
  81 is positive infinity, positive infinity is returned.
  82
  83 If
  84 .I x
  85 is less than \-0,
  86 a domain error occurs,
  87 and a NaN is returned.
  88 .SH ERRORS
  89 See
  90 .BR math_error (7)
  91 for information on how to determine whether an error has occurred
  92 when calling these functions.
  93 .PP
  94 The following errors can occur:
  95 .TP
  96 Domain error: \fIx\fP less than \-0
  97 .I errno
  98 is set to
  99 .BR EDOM .
 100 An invalid floating-point exception
 101 .RB ( FE_INVALID )
 102 is raised.
 103 .SH ATTRIBUTES
 104 For an explanation of the terms used in this section, see
 105 .BR attributes (7).
 106 .TS
 107 allbox;
 108 lbw24 lb lb
 109 l l l.
 110 Interface       Attribute       Value
 111 T{
 112 .BR sqrt (),
 113 .BR sqrtf (),
 114 .BR sqrtl ()
 115 T}      Thread safety   MT-Safe
 116 .TE
 117 .SH CONFORMING TO
 118 C99, POSIX.1-2001, POSIX.1-2008.
 119
 120 The variant returning
 121 .I double
 122 also conforms to
 123 SVr4, 4.3BSD, C89.
 124 .SH SEE ALSO
 125 .BR cbrt (3),
 126 .BR csqrt (3),
 127 .BR hypot (3)