**#include <math.h>
**

**
double hypot(double** *x***, double** *y***);
float hypotf(float**

long double hypotl(long double

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.

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.

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.*

*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 computation.

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.

*feclearexcept*() , *fetestexcept*() , *isnan*() , *sqrt*()
, the Base Definitions volume of
IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Conditions
for
Mathematical Functions, *<math.h>*

- NAME
- SYNOPSIS
- DESCRIPTION
- RETURN VALUE
- ERRORS
- EXAMPLES
- APPLICATION USAGE
- RATIONALE
- FUTURE DIRECTIONS
- SEE ALSO
- COPYRIGHT

Time: 21:48:04 GMT, April 16, 2011