Originální popis anglicky:
hypot, hypotf, hypotl - Euclidean distance function
Návod, kniha: POSIX Programmer's Manual
#include <math.h>
double hypot(double
x, double
y );
float hypotf(float
x, float
y);
long double hypotl(long double
x, long double
y);
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.
None.
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.
None.
None.
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>
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 original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
