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Path: utzoo!utgpu!water!watmath!mks!tj
From: tj@mks.UUCP
Newsgroups: comp.bugs.sys5,comp.sys.hp
Subject: Re: pow(3M) may have a bug or undocumented limitation
Message-ID: <266@mks.UUCP>
Date: Mon, 18-May-87 13:33:54 EDT
Article-I.D.: mks.266
Posted: Mon May 18 13:33:54 1987
Date-Received: Tue, 19-May-87 01:29:41 EDT
References: <226@cogent.UUCP>
Organization: Mortice Kern Systems, Waterloo, Ont.
Lines: 25
Keywords: x^y y<0 DOMAIN error
Xref: utgpu comp.bugs.sys5:118 comp.sys.hp:137
Summary: probable arg type error

In article <226@cogent.UUCP>, mark@cogent.UUCP (Captain Neptune) writes:
> 
> I am running an HP 9000/840 running HP-UX and I have a problem doing some math.
> I am trying to use pow(3M) to raise a positive integer value to a negative
> integer value.  For example, the 12th root of 2 --> 2 ^ (-12) --> pow(2,-12).
> 
> I keep getting "DOMAIN error" even though the manual page doesn't seem to
> cite this case as an illegal one.  It would be illegal if, say, the first
> argument was zero, for instance.  Pow(3M) is found on the manual page for
> "exp(3M)".

My guess is that you have neglected ensure that the arguments passed to pow
are doubles. try pow(2.0, -12.0);
BTW the 12th root of 2 is 2^(1/12) i.e. pow(2.0, 1.0/12.0);

V7 and BSD man page say that pow gives domain error when 2nd argument
is negative and non-integral. This is wrong. SYSV man page correctly
states that domain error results when 1st arg is negative and 2nd is
non-integral.

-- 
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