From: "Tharaneedharan Vilwanathan" <vdharani@gmail.com>
To: "Fans of the OS Plan 9 from Bell Labs" <9fans@9fans.net>
Subject: Re: [9fans] a bug in awk?
Date: Sun, 11 Jan 2009 01:30:05 -0800 [thread overview]
Message-ID: <dac0a5820901110130m31ce8ee3hcdeef61215ab10b7@mail.gmail.com> (raw)
In-Reply-To: <1f008c20c3fcaf5ebcc59a63642a32fb@quanstro.net>
hi erik,
i had a temp code in dumvacroots.new:
...
rc |
awk '/5946903e/ { next; }
$3==16 {printf("%s\n", $0)}'
which i removed it now, built awk with your fix in place and tried.
the problem is fixed now.
thanks for the fix.
regards
dharani
On Sat, Jan 10, 2009 at 1:45 PM, erik quanstrom <quanstro@quanstro.net> wrote:
>> For what it's worth, bwk awk does not have this problem, so the error
>> must be in code introduced later.
>>
>>> Note the 5946903e318 which AWK may mistakenly treat as a floating
>>> point constant. Now to figure how to prevent such errors...
>
> from the better than nothin' department ...
>
> i have an inelegant couple of lines that prevent overflow.
>
> one would expect that for a postitive exponent that if
> nwholedigits + exponent - 1 > the maximum exp.
> then you'll have an overflow. (ideally one should do this
> computation in ieee space, but that's not what the code
> does.) i put this simple test in the natural place and
> it seems to avoid the floating point exception (tested on intel
> machines). the problem seems to be that the code deals
> with very small overflows, but isn't prepared to deal with
> a number that's going to overflow by a lot. in this case,
> we're 1^(10 + 6) too big.
>
> ; diffy strtod.c
> 396a397,398
>> if(nd0 + e1 - 1> DBL_MAX_10_EXP)
>> goto ovfl;
> 431a434,435
>> if(e1 - (nd-nd0) > DBL_MAX_10_EXP)
>> goto undfl;
>
> is it even legal to return DBL_MAX for numbers that should
> be +Inf or DBL_MIN for numbers that should yield -Inf?
>
> is there some reason that the regular strtod is unsuitable for
> ape?
>
> - erik
>
>
>
next prev parent reply other threads:[~2009-01-11 9:30 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-10 21:45 erik quanstrom
2009-01-11 7:07 ` Russ Cox
2009-01-11 7:24 ` erik quanstrom
2009-01-11 9:30 ` Tharaneedharan Vilwanathan [this message]
-- strict thread matches above, loose matches on Subject: below --
2009-01-10 5:57 Tharaneedharan Vilwanathan
2009-01-10 6:26 ` lucio
2009-01-10 6:39 ` Tharaneedharan Vilwanathan
2009-01-10 16:19 ` John Stalker
2009-01-10 19:43 ` erik quanstrom
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