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man pages->FreeBSD man pages -> hypot (3)
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## HYPOT(3)

```
```

### NAME[Toc][Back]

```     hypot, hypotf, cabs, cabsf -- Euclidean distance and complex absolute
value functions
```

### LIBRARY[Toc][Back]

```     Math Library (libm, -lm)
```

### SYNOPSIS[Toc][Back]

```     #include <math.h>

double
hypot(double x, double y);

float
hypotf(float x, float y);

struct {double x, y;} z;

double
cabs(z);

struct {float x, y;} z;

float
cabsf(z);
```

### DESCRIPTION[Toc][Back]

```     The hypot(), hypotf(), cabs() and cabsf() 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.

ERROR (due to Roundoff, etc.)
Below 0.97 ulps.  Consequently hypot(5.0, 12.0) = 13.0 exactly; in general,
hypot and cabs return an integer whenever an integer might be
expected.

The same cannot be said for the shorter and faster version of hypot and
cabs that is provided in the comments in cabs.c; its error can exceed 1.2
ulps.
```

### NOTES[Toc][Back]

```     As might be expected, 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 (if 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).
```

```     math(3), sqrt(3)
```

### HISTORY[Toc][Back]

```     Both a hypot() function and a cabs() function appeared in Version 7 AT&T
UNIX.

FreeBSD 5.2.1			  May 6, 1991			 FreeBSD 5.2.1```
[ Back ]
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