DragonFly On-Line Manual Pages
HYPOT(3) DragonFly Library Functions Manual HYPOT(3)
hypot, hypotf, hypotl, cabs, cabsf, cabsl -- Euclidean distance and com-
plex absolute value functions
Math Library (libm, -lm)
hypot(double x, double y);
hypotf(float x, float y);
hypotl(long double x, long double y);
cabs(double complex z);
cabsf(float complex z);
cabsl(long double complex z);
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
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
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).
carg(3), math(3), sqrt(3)
The hypot(), hypotf(), hypotl(), cabs(), cabsf(), and cabsl() functions
conform to ISO/IEC 9899:1999 (``ISO C99'').
Both a hypot() function and a cabs() function appeared in Version 7 AT&T
DragonFly 4.3 December 21, 2011 DragonFly 4.3