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).

SEE ALSO

carg(3), math(3), sqrt(3)

STANDARDS

The hypot(), hypotf(), hypotl(), cabs(), cabsf(), and cabsl() functions conform to ISO/IEC 9899:1999 (``ISO C99'').

HISTORY

Both a hypot() function and a cabs() function appeared in Version 7 AT&T UNIX. DragonFly 3.7 December 21, 2011 DragonFly 3.7