SQRT(P)                                                                                   SQRT(P)



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
       These functions shall compute the square root of their argument x, sqrt(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 either a NaN (if supported), or an implemen-
       tation-defined value 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
       IEEE Std 1003.1-2001,  Section  4.18, Treatment of Error Conditions for Mathematical Func-
       tions, <math.h>, <stdio.h>

COPYRIGHT
       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. 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 Standard is the referee document. The orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .



POSIX                                          2003                                       SQRT(P)