1SQRT(3P) POSIX Programmer's Manual SQRT(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10 delim $$
12
14 sqrt, sqrtf, sqrtl — square root function
15
17 #include <math.h>
18 double sqrt(double x);
20 float sqrtf(float x);
21 long double sqrtl(long double x);
22
24 The functionality described on this reference page is aligned with the
25 ISO C standard. Any conflict between the requirements described here
26 and the ISO C standard is unintentional. This volume of POSIX.1‐2008
27 defers to the ISO C standard.
28 These functions shall compute the square root of their argument x,
30 $sqrt {x}$.
31 An application wishing to check for error situations should set errno
33 to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these
34 functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
35 FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
36 occurred.
37
39 Upon successful completion, these functions shall return the square
40 root of x.
41 For finite values of x < −0, a domain error shall occur, and either a
43 NaN (if supported), or an implementation-defined value shall be
44 returned.
45 If x is NaN, a NaN shall be returned.
47 If x is ±0 or +Inf, x shall be returned.
49 If x is −Inf, a domain error shall occur, and a NaN shall be returned.
51
53 These functions shall fail if:
54 Domain Error
56 The finite value of x is < −0, or x is −Inf.
57 If the integer expression (math_errhandling & MATH_ERRNO)
59 is non-zero, then errno shall be set to [EDOM]. If the
60 integer expression (math_errhandling & MATH_ERREXCEPT) is
61 non-zero, then the invalid floating-point exception shall
62 be raised.
63 The following sections are informative.
65
67 Taking the Square Root of 9.0
68 #include <math.h>
69 ...
70 double x = 9.0;
71 double result;
72 ...
73 result = sqrt(x);
74
76 On error, the expressions (math_errhandling & MATH_ERRNO) and
77 (math_errhandling & MATH_ERREXCEPT) are independent of each other, but
78 at least one of them must be non-zero.
79
81 None.
82
84 None.
85
87 feclearexcept(), fetestexcept(), isnan()
88 The Base Definitions volume of POSIX.1‐2008, Section 4.19, Treatment of
90 Error Conditions for Mathematical Functions, <math.h>, <stdio.h>
91
93 Portions of this text are reprinted and reproduced in electronic form
94 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
95 -- Portable Operating System Interface (POSIX), The Open Group Base
96 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
97 cal and Electronics Engineers, Inc and The Open Group. (This is
98 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
99 event of any discrepancy between this version and the original IEEE and
100 The Open Group Standard, the original IEEE and The Open Group Standard
101 is the referee document. The original Standard can be obtained online
102 at http://www.unix.org/online.html .
103 Any typographical or formatting errors that appear in this page are
105 most likely to have been introduced during the conversion of the source
106 files to man page format. To report such errors, see https://www.ker‐
107 nel.org/doc/man-pages/reporting_bugs.html .
108IEEE/The Open Group 2013 SQRT(3P)