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
12 sqrt, sqrtf, sqrtl — square root function
13
15 #include <math.h>
16 double sqrt(double x);
18 float sqrtf(float x);
19 long double sqrtl(long double x);
20
22 The functionality described on this reference page is aligned with the
23 ISO C standard. Any conflict between the requirements described here
24 and the ISO C standard is unintentional. This volume of POSIX.1‐2017
25 defers to the ISO C standard.
26 These functions shall compute the square root of their argument x, √x.
28 An application wishing to check for error situations should set errno
30 to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these
31 functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
32 FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
33 occurred.
34
36 Upon successful completion, these functions shall return the square
37 root of x.
38 For finite values of x < -0, a domain error shall occur, and either a
40 NaN (if supported), or an implementation-defined value shall be
41 returned.
42 If x is NaN, a NaN shall be returned.
44 If x is ±0 or +Inf, x shall be returned.
46 If x is -Inf, a domain error shall occur, and a NaN shall be returned.
48
50 These functions shall fail if:
51 Domain Error
53 The finite value of x is < -0, or x is -Inf.
54 If the integer expression (math_errhandling & MATH_ERRNO)
56 is non-zero, then errno shall be set to [EDOM]. If the
57 integer expression (math_errhandling & MATH_ERREXCEPT) is
58 non-zero, then the invalid floating-point exception shall
59 be raised.
60 The following sections are informative.
62
64 Taking the Square Root of 9.0
65 #include <math.h>
66 ...
67 double x = 9.0;
68 double result;
69 ...
70 result = sqrt(x);
71
73 On error, the expressions (math_errhandling & MATH_ERRNO) and
74 (math_errhandling & MATH_ERREXCEPT) are independent of each other, but
75 at least one of them must be non-zero.
76
78 None.
79
81 None.
82
84 feclearexcept(), fetestexcept(), isnan()
85 The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of
87 Error Conditions for Mathematical Functions, <math.h>, <stdio.h>
88
90 Portions of this text are reprinted and reproduced in electronic form
91 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
92 table Operating System Interface (POSIX), The Open Group Base Specifi‐
93 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
94 Electrical and Electronics Engineers, Inc and The Open Group. In the
95 event of any discrepancy between this version and the original IEEE and
96 The Open Group Standard, the original IEEE and The Open Group Standard
97 is the referee document. The original Standard can be obtained online
98 at http://www.opengroup.org/unix/online.html .
99 Any typographical or formatting errors that appear in this page are
101 most likely to have been introduced during the conversion of the source
102 files to man page format. To report such errors, see https://www.ker‐
103 nel.org/doc/man-pages/reporting_bugs.html .
104IEEE/The Open Group 2017 SQRT(3P)