Help with a possible bug

*To*: mathgroup at smc.vnet.net*Subject*: [mg98870] Help with a possible bug*From*: M8R-lj1smh at mailinator.com*Date*: Mon, 20 Apr 2009 19:11:24 -0400 (EDT)

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 in 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"]

**Follow-Ups**:**Re: Help with a possible bug***From:*Arnoud Buzing <arnoudb@wolfram.com>