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HYPOT(P)			    POSIX Programmer's Manual				 HYPOT(P)

NAME
       hypot, hypotf, hypotl - Euclidean distance function

SYNOPSIS
       #include <math.h>

       double hypot(double x, double y);
       float hypotf(float x, float y);
       long double hypotl(long double x, long double y);

DESCRIPTION
       These  functions  shall	compute  the value of the square root of x**2+ y**2 without undue
       overflow or underflow.

       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 length of the hypotenuse of a
       right-angled triangle with sides of length x and y.

       If the correct value would  cause  overflow,  a	range  error  shall  occur  and  hypot(),
       hypotf(),  and  hypotl()  shall	return	the  value  of the macro HUGE_VAL, HUGE_VALF, and
       HUGE_VALL, respectively.

       If x or y is +-Inf, +Inf shall be returned (even if one of x or y is NaN).

       If x or y is NaN, and the other is not +-Inf, a NaN shall be returned.

       If both arguments are subnormal and the correct result is subnormal,  a	range  error  may
       occur and the correct result is returned.

ERRORS
       These functions shall fail if:

       Range Error
	      The result overflows.

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

       These functions may fail if:

       Range Error
	      The result underflows.

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

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       hypot(x,y), hypot(y,x), and hypot(x, -y) are equivalent.

       hypot(x, +-0) is equivalent to fabs(x).

       Underflow  only	happens  when both x and y are subnormal and the (inexact) result is also
       subnormal.

       These functions take precautions against overflow during intermediate steps of the  compu-
       tation.

       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() , sqrt()  ,  the  Base  Definitions  volume  of
       IEEE Std 1003.1-2001,  Section  4.18, Treatment of Error Conditions for Mathematical Func-
       tions, <math.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 .

IEEE/The Open Group			       2003					 HYPOT(P)
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