# DragonFly On-Line Manual Pages

```HYPOT(3)	      DragonFly Library Functions Manual	      HYPOT(3)

NAME
hypot, hypotf, hypotl, cabs, cabsf, cabsl -- Euclidean distance and com-
plex absolute value functions

LIBRARY
Math Library (libm, -lm)

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);

#include <complex.h>

double
cabs(double complex z);

float
cabsf(float complex z);

long double
cabsl(long double complex z);

DESCRIPTION
The hypot(), hypotf() and hypotl() 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.  The cabs(), cabsf() and cabsl() functions
compute the complex absolute value of z.

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 gen-
eral, hypot and cabs return an integer whenever an integer might be
expected.

NOTES
As might be expected, hypot(v, NaN) and hypot(NaN, v) are NaN for all
finite v.	But programmers 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 oper-
and 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).