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>
   4 .\"
   5 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   6 .\"
   7 .\" References consulted:
   8 .\"     Linux libc source code
   9 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  10 .\"     386BSD man pages
  11 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
  12 .\" Modified 2002-07-27 by Walter Harms
  13 .\"     (walter.harms@informatik.uni-oldenburg.de)
  14 .TH SQRT 3 2021-03-22 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
  15 .SH NAME
  16 sqrt, sqrtf, sqrtl \- square root function
  17 .SH LIBRARY
  18 Math library
  19 .RI ( libm ", " \-lm )
  20 .SH SYNOPSIS
  21 .nf
  22 .B #include <math.h>
  23 .PP
  24 .BI "double sqrt(double " x );
  25 .BI "float sqrtf(float " x );
  26 .BI "long double sqrtl(long double " x );
  27 .fi
  28 .PP
  29 .RS -4
  30 Feature Test Macro Requirements for glibc (see
  31 .BR feature_test_macros (7)):
  32 .RE
  33 .PP
  34 .BR sqrtf (),
  35 .BR sqrtl ():
  36 .nf
  37     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  38         || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  39         || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  40 .fi
  41 .SH DESCRIPTION
  42 These functions return the nonnegative square root of
  43 .IR x .
  44 .SH RETURN VALUE
  45 On success, these functions return the square root of
  46 .IR x .
  47 .PP
  48 If
  49 .I x
  50 is a NaN, a NaN is returned.
  51 .PP
  52 If
  53 .I x
  54 is +0 (\-0), +0 (\-0) is returned.
  55 .PP
  56 If
  57 .I x
  58 is positive infinity, positive infinity is returned.
  59 .PP
  60 If
  61 .I x
  62 is less than \-0,
  63 a domain error occurs,
  64 and a NaN is returned.
  65 .SH ERRORS
  66 See
  67 .BR math_error (7)
  68 for information on how to determine whether an error has occurred
  69 when calling these functions.
  70 .PP
  71 The following errors can occur:
  72 .TP
  73 Domain error: \fIx\fP less than \-0
  74 .I errno
  75 is set to
  76 .BR EDOM .
  77 An invalid floating-point exception
  78 .RB ( FE_INVALID )
  79 is raised.
  80 .SH ATTRIBUTES
  81 For an explanation of the terms used in this section, see
  82 .BR attributes (7).
  83 .ad l
  84 .nh
  85 .TS
  86 allbox;
  87 lbx lb lb
  88 l l l.
  89 Interface       Attribute       Value
  90 T{
  91 .BR sqrt (),
  92 .BR sqrtf (),
  93 .BR sqrtl ()
  94 T}      Thread safety   MT-Safe
  95 .TE
  96 .hy
  97 .ad
  98 .sp 1
  99 .SH STANDARDS
 100 C99, POSIX.1-2001, POSIX.1-2008.
 101 .PP
 102 The variant returning
 103 .I double
 104 also conforms to
 105 SVr4, 4.3BSD, C89.
 106 .SH SEE ALSO
 107 .BR cbrt (3),
 108 .BR csqrt (3),
 109 .BR hypot (3)