man3/sqrt.3

   1 '\" t
   2 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
   3 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
   4 .\"     <mtk.manpages@gmail.com>
   5 .\"
   6 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   7 .\"
   8 .\" References consulted:
   9 .\"     Linux libc source code
  10 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  11 .\"     386BSD man pages
  12 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
  13 .\" Modified 2002-07-27 by Walter Harms
  14 .\"     (walter.harms@informatik.uni-oldenburg.de)
  15 .TH sqrt 3 (date) "Linux man-pages (unreleased)"
  16 .SH NAME
  17 sqrt, sqrtf, sqrtl \- square root function
  18 .SH LIBRARY
  19 Math library
  20 .RI ( libm ", " \-lm )
  21 .SH SYNOPSIS
  22 .nf
  23 .B #include <math.h>
  24 .PP
  25 .BI "double sqrt(double " x );
  26 .BI "float sqrtf(float " x );
  27 .BI "long double sqrtl(long double " x );
  28 .fi
  29 .PP
  30 .RS -4
  31 Feature Test Macro Requirements for glibc (see
  32 .BR feature_test_macros (7)):
  33 .RE
  34 .PP
  35 .BR sqrtf (),
  36 .BR sqrtl ():
  37 .nf
  38     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  39         || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  40         || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  41 .fi
  42 .SH DESCRIPTION
  43 These functions return the nonnegative square root of
  44 .IR x .
  45 .SH RETURN VALUE
  46 On success, these functions return the square root of
  47 .IR x .
  48 .PP
  49 If
  50 .I x
  51 is a NaN, a NaN is returned.
  52 .PP
  53 If
  54 .I x
  55 is +0 (\-0), +0 (\-0) is returned.
  56 .PP
  57 If
  58 .I x
  59 is positive infinity, positive infinity is returned.
  60 .PP
  61 If
  62 .I x
  63 is less than \-0,
  64 a domain error occurs,
  65 and a NaN is returned.
  66 .SH ERRORS
  67 See
  68 .BR math_error (7)
  69 for information on how to determine whether an error has occurred
  70 when calling these functions.
  71 .PP
  72 The following errors can occur:
  73 .TP
  74 Domain error: \fIx\fP less than \-0
  75 .I errno
  76 is set to
  77 .BR EDOM .
  78 An invalid floating-point exception
  79 .RB ( FE_INVALID )
  80 is raised.
  81 .SH ATTRIBUTES
  82 For an explanation of the terms used in this section, see
  83 .BR attributes (7).
  84 .ad l
  85 .nh
  86 .TS
  87 allbox;
  88 lbx lb lb
  89 l l l.
  90 Interface       Attribute       Value
  91 T{
  92 .BR sqrt (),
  93 .BR sqrtf (),
  94 .BR sqrtl ()
  95 T}      Thread safety   MT-Safe
  96 .TE
  97 .hy
  98 .ad
  99 .sp 1
 100 .SH STANDARDS
 101 C11, POSIX.1-2008.
 102 .SH HISTORY
 103 C99, POSIX.1-2001.
 104 .PP
 105 The variant returning
 106 .I double
 107 also conforms to
 108 SVr4, 4.3BSD, C89.
 109 .SH SEE ALSO
 110 .BR cbrt (3),
 111 .BR csqrt (3),
 112 .BR hypot (3)