HYPOT(3) | Library Functions Manual | HYPOT(3) |
hypot
, hypotf
,
hypotl
—
#include <math.h>
double
hypot
(double
x, double y);
float
hypotf
(float
x, float y);
long double
hypotl
(long
double x, long double
y);
#include
<tgmath.h>
real-floating
hypot
(real-floating,
real-floating);
hypot
() functions compute the sqrt(x*x+y*y) in such
a way that underflow will not happen, and overflow occurs only if the final
result deserves it.
hypot
(infinity,
v) =
hypot
(v,
infinity) = +infinity for all v,
including NaN.
hypot
(5.0,
12.0) = 13.0 exactly; in general, hypot returns an
integer whenever an integer might be expected.
The same cannot be said for the shorter and faster version of hypot that is provided in the comments in cabs.c; its error can exceed 1.2 ulps.
hypot
(v,
NaN) and
hypot
(NaN,
v) are NaN for all finite
v; with "reserved operand" in place of
"NaN", the same is true on a VAX. But programmers on machines other
than a VAX (it has no infinity) might be surprised at first to discover that
hypot
(±infinity,
NaN) = +infinity. This is intentional; it happens
because hypot
(infinity,
v) = +infinity for all
v, finite or infinite. Hence
hypot
(infinity,
v) is independent of v. Unlike the
reserved operand fault on a VAX, the IEEE NaN is designed to disappear when it
turns out to be irrelevant, as it does in
hypot
(infinity,
NaN).
hypot
() appeared in
Version 7 AT&T UNIX.
September 26, 2017 | NetBSD 9.0 |