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From: gwyn@smoke.brl.mil (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: In search of cbrt() ...
Keywords: Gaphics Gems, cbrt() for TC++
Message-ID: <14739@smoke.brl.mil>
Date: 14 Dec 90 20:55:06 GMT
References: <Dec.12.18.31.04.1990.3356@paul.rutgers.edu> <14724@smoke.brl.mil> <4502@goanna.cs.rmit.oz.au>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 10

In article <4502@goanna.cs.rmit.oz.au> ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe) writes:
>> However, if all it does is extract a cube-root, it's trivial to emulate:
>> 	#include <math.h>
>> 	#define cubrt(x) pow(x,1.0/3.0)
>That doesn't quite do the job.  cbrt(-8.0) is -2.0, but pow(-8.0, 1.0/3.0)
>prints "DOMAIN error" and returns 0.0.

Obviously.  And there are also complex cube roots, etc.  I assumed
that the operand was non-negative for simplicity, since it might be
known to be so in the particular application.