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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>

     hypot(double x, double y);

     hypotf(float x, float y);

     struct {double x, y;} z;


     struct {float x, y;} 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

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

     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

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).

SEE ALSO    [Toc]    [Back]

     math(3), sqrt(3)

HISTORY    [Toc]    [Back]

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

FreeBSD 5.2.1			  May 6, 1991			 FreeBSD 5.2.1
[ Back ]
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