HYPOT

Section: C Library Functions (3)
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BSD mandoc
BSD 4

NAME

hypot cabs - euclidean distance and complex absolute value functions

SYNOPSIS

Fd #include <math.h> Ft double Fn hypot double x double y Fd struct {double x, y;} z; Ft double Fn cabs z

DESCRIPTION

The Fn hypot and Fn cabs functions computes 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.

Fn hypot v = Fn hypot v = + for all v including .

ERROR (due to Roundoff, etc.)

Below 0.97 ulps Consequently Fn hypot 5.0 12.0 = 13.0 exactly; in general, hypot and cabs return an integer whenever an integer might be expected.

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 ulps

NOTES

As might be expected, Fn hypot v and Fn hypot v are for all finite v with "reserved operand" in place of "", the same is true on a VAX But programmers on machines other than a VAX (if has no ) might be surprised at first to discover that Fn hypot ± = +. This is intentional; it happens because Fn hypot v = + for all v finite or infinite. Hence Fn hypot v is independent of v Unlike the reserved operand fault on a VAX the IEEE is designed to disappear when it turns out to be irrelevant, as it does in Fn hypot .

HISTORY

Both a Fn hypot function and a Fn cabs function appeared in AT&T System v7 .

This document was created by man2html, using the manual pages.
Time: 16:10:48 GMT, January 15, 2023