Re: Help with a possible bug
- To: mathgroup at smc.vnet.net
- Subject: [mg98940] Re: Help with a possible bug
- From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
- Date: Wed, 22 Apr 2009 05:12:21 -0400 (EDT)
- References: <gsivea$9bt$1@smc.vnet.net>
Probably mac-related. I don't get this behavior on my $Version
"7.0 for Microsoft Windows (32-bit) (February 18, 2009)"
Cheers -- Sjoerd
On Apr 21, 1:11 am, M8R-lj1... at mailinator.com wrote:
> At work we seem to have stumbled on a strange bug between Table and
> Part. We can reproduce the bug on differently configured Mac and
> Linux boxes. I tried Wolfram support, but they claim they cannot
> reproduce the bug. So I was hoping someone could try it out and
> report their results. Thanks in advance to all volunteers.
>
> For us, the bug is new in 7.0.1. It does not show up in version 6.
> To reproduce it, fill up a 17 x 267 matrix with 3s. Compute the sum
> of some of the columns and you get the result 51 (17 x 3). But if one
> computes the sum for the last few columns, the result is completely
> off. The bug seems to arise from the interaction of optimizations i=
n
> Table and the use of All inside of Part.
>
> ------------ code
>
> mat = Table[3, {i, 1, 17}, {j, 1, 267}];
>
> sum = Table[Total[mat[[All, j]]], {j, 1, 249}]
>
> sum1 = Table[Total[mat[[All, j]]], {j, 1, 252}];
> sum2 = Table[Total[mat[[All, j]]], {j, 1, 252}]
>
> ------------ end code
>
> If you look at sum1, it will be correct on a fresh copy of the
> Kernel. The problem only arise from the second time on.
>
> Thanks,
>
> Papin
>
> Email: ImportString["cGFwaW5AY294Lm5ldA==", "Base64"]