From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <001601bffafd$f5763d60$0500a8c0@telusplanet.net>
From: "Doug Henderson" <djhender@telusplanet.net>
To: <9fans@cse.psu.edu>
References: <200007310627.CAA07797@cse.psu.edu>
Subject: Re: [9fans] Problem with native vs APE math
Date: Mon, 31 Jul 2000 08:40:34 -0600
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On my Celeron, I get log(1)=0, log(0)=-HUGE_VAL and log(-1)=-HUGE_VAL, which
is what I expect from reading the code for log in
/sys/src/ape/lib/ap/math/log.c, and errno is set to ERANGE for log(0) and
EDOM for log(-1).

Clearing the FPINVAL bit in the pcr gets rid of the suicides.

There is an undocumented bit set in psr after log(0).
Also, there is a mismatch between some defines in ape/float.h and
ape/sys/fp.h

----- Original Message -----
From: "Russ Cox" <rsc@plan9.bell-labs.com>
To: <djhender@telusplanet.net>; <9fans@cse.psu.edu>
Sent: Monday, July 31, 2000 12:27 AM
Subject: Re: [9fans] Problem with native vs APE math


> When I compile that using APE I get 0.00000
> for all the answers, which is not what I expected
> but not unreasonable given the code.
> I don't think that the APE libraries use Inf and NaN.
>
> As for why it crashes natively, you need to
> turn off some exceptions related to use of
> Inf and NaN -- see getfcr(2).
>
> Russ
>