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  2015-03-02 ""  "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 .sp
  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 .sp
  48 Link with \fI\-lm\fP.
  49 .sp
  50 .in -4n
  51 Feature Test Macro Requirements for glibc (see
  52 .BR feature_test_macros (7)):
  53 .in
  54 .sp
  55 .ad l
  56 .BR sqrtf (),
  57 .BR sqrtl ():
  58 .RS 4
  59 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
  60 _POSIX_C_SOURCE\ >=\ 200112L;
  61 .br
  62 or
  63 .I cc\ -std=c99
  64 .RE
  65 .ad
  66 .SH DESCRIPTION
  67 These functions return the nonnegative square root of
  68 .IR x .
  69 .SH RETURN VALUE
  70 On success, these functions return the square root of
  71 .IR x .
  72
  73 If
  74 .I x
  75 is a NaN, a NaN is returned.
  76
  77 If
  78 .I x
  79 is +0 (\-0), +0 (\-0) is returned.
  80
  81 If
  82 .I x
  83 is positive infinity, positive infinity is returned.
  84
  85 If
  86 .I x
  87 is less than \-0,
  88 a domain error occurs,
  89 and a NaN is returned.
  90 .SH ERRORS
  91 See
  92 .BR math_error (7)
  93 for information on how to determine whether an error has occurred
  94 when calling these functions.
  95 .PP
  96 The following errors can occur:
  97 .TP
  98 Domain error: \fIx\fP less than \-0
  99 .I errno
 100 is set to
 101 .BR EDOM .
 102 An invalid floating-point exception
 103 .RB ( FE_INVALID )
 104 is raised.
 105 .SH ATTRIBUTES
 106 For an explanation of the terms used in this section, see
 107 .BR attributes (7).
 108 .TS
 109 allbox;
 110 lbw24 lb lb
 111 l l l.
 112 Interface       Attribute       Value
 113 T{
 114 .BR sqrt (),
 115 .BR sqrtf (),
 116 .BR sqrtl ()
 117 T}      Thread safety   MT-Safe
 118 .TE
 119 .SH CONFORMING TO
 120 C99, POSIX.1-2001, POSIX.1-2008.
 121
 122 The variant returning
 123 .I double
 124 also conforms to
 125 SVr4, 4.3BSD, C89.
 126 .SH SEE ALSO
 127 .BR cbrt (3),
 128 .BR csqrt (3),
 129 .BR hypot (3)