posix man page for sqrt

SQRT(3P)						     POSIX Programmer's Manual							  SQRT(3P)

PROLOG
       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME
       sqrt, sqrtf, sqrtl -- square root function

SYNOPSIS
       #include <math.h>

       double sqrt(double x);
       float sqrtf(float x);
       long double sqrtl(long double x);

DESCRIPTION
       The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here
       and the ISO C standard is unintentional. This volume of POSIX.1-2008 defers to the ISO C standard.

       These functions shall compute the square root of their argument x, x.

       An  application	wishing  to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these
       functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is  non-zero,  an  error
       has occurred.

RETURN VALUE
       Upon successful completion, these functions shall return the square root of x.

       For  finite  values  of	x  <  -0, a domain error shall occur, and either a NaN (if supported), or an implementation-defined value shall be
       returned.

       If x is NaN, a NaN shall be returned.

       If x is +-0 or +Inf, x shall be returned.

       If x is -Inf, a domain error shall occur, and a NaN shall be returned.

ERRORS
       These functions shall fail if:

       Domain Error
		   The finite value of x is < -0, or x is -Inf.

		   If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be  set  to	[EDOM].   If  the  integer
		   expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised.

       The following sections are informative.

EXAMPLES
   Taking the Square Root of 9.0
	   #include <math.h>
	   ...
	   double x = 9.0;
	   double result;
	   ...
	   result = sqrt(x);

APPLICATION USAGE
       On  error,  the	expressions  (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other, but at
       least one of them must be non-zero.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       feclearexcept(), fetestexcept(), isnan()

       The Base Definitions volume of POSIX.1-2008, Section 4.19, Treatment of Error Conditions for Mathematical Functions, <math.h>, <stdio.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technol-
       ogy  --	Portable  Operating  System  Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
       event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Stan-
       dard is the referee document. The original Standard can be obtained online at http://www.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE
/The Open Group						       2013								  SQRT(3P)