Req #52734 [Opn->Wfx]: Extend hypot() to three dimensions

Edit report at http://bugs.php.net/bug.php?id=52734&edit=1 ID: 52734 Updated by: aharvey@php.net Reported by: a at b dot c dot de Summary: Extend hypot() to three dimensions -Status: Open +Status: Wont fix Type: Feature/Change Request Package: Math related Operating System: Windows XP PHP Version: 5.3.3 Block user comment: N New Comment: hypot() was intended to be (and is generally implemented as) a wrapper for the C99 and POSIX hypot() function, which itself only accepts two dimensions. Given that this can be easily implemented in PHP itself using sqrt() (as you demonstrate), I don't see any real benefit in diverging from the underlying implementation. Previous Comments: ------------------------------------------------------------------------ [2010-08-30 06:50:00] a at b dot c dot de Description: ------------ The existing hypot() function is limited to finding the hypotenuse of a right-angled triangle in two dimensions ($h = hypot($x,$y)), when in fact it is well-defined for higher dimensions as well as the length of the diagonal of a (hyper)cuboid with edge lengths $x,$y,$z...; it's the square root of the sum of the squares of the edge lengths. For geometric purposes it would be helpful to have at least hypot($x,$y,$z). The existing alternatives are sqrt($x*$x+$y*$y+$z*$z) or hypot(hypot($x,$y),$z). The latter is (not surprisingly) markedly slower, and also less accurate. Test script: --------------- function length($v1, $v2) { return hypot($v1[0]-$v2[0], $v1[1]-$v2[1], $v1[2]-$v2[2]); } $v1 = array(1, 1, 1); $v2 = array(5, 6, 1); echo length($v1, $v2); Expected result: ---------------- 6.4031242374328 Actual result: -------------- A warning about hypot expecting exactly two parameters, and a NULL return value. ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=52734&edit=1