netbsd man page for hypot

HYPOT(3)						   BSD Library Functions Manual 						  HYPOT(3)

NAME
     hypot, hypotf -- Euclidean distance and complex absolute value functions

LIBRARY
     Math Library (libm, -lm)

SYNOPSIS
     #include <math.h>

     double
     hypot(double x, double y);

     float
     hypotf(float x, float y);

DESCRIPTION
     The 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.

ERRORS
     Below 0.97 ulps.  Consequently 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.

NOTES
     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 (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).

SEE ALSO
     math(3), sqrt(3)

HISTORY
     Both a hypot() function and a cabs() function appeared in Version 7 AT&T UNIX.  cabs() was removed from public namespace in NetBSD 5.0 to
     avoid conflicts with the complex function in C99.

BSD
								 February 12, 2007							       BSD