Software Carpentry

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Archive for October 2006

Computational Result Retracted

From the latest Nature (Vol 443, No 7114, p 1013):

When a new, independent code is used for the calculations on which the conclusions of this Letter were based, the results reported for the evolution of obliquity cannot be reproduced. This code was written in the inertial frame and is more reliable than the one used in the Letter. In most runs, the obliquities can change by only a few degrees and attain large values in only a very few cases. In addition, the obliquity variation shown in the Supplementary Information, although correct, originates from changes to orbital inclination of the planet, and close encounters are not effective in causing large obliquities.

In other words, the code was flaky, so the results we published were wrong. Kudos to the author for trying to verify his result with another program—I’m sure a lot of computational scientists would be very embarrassed if they had to do the same. But I wonder: why does he believe the “new code” is more reliable? Surely not just because it uses a more sophisticated method, or gives a less surprising answer…

(Thanks to Andrew Straw for the pointer.)


Written by Greg Wilson

2006/10/31 at 09:35

Posted in Content

German Version of “Bottleneck”

A German version of my article “Where’s the Real Bottleneck in Scientific Computing?” has just appeared in Spektrum magazine. Pay-per-view, unfortunately, but the Software Carpentry site has had a flurry of hits from .de domains.

Dec 1: I just received my copy in the mail—I sound so much…sterner…in German 😉

Gregory V. Wilson ist Professor für Computerwissenschaft an der University of Toronto. Sein Kurs ist erhältlich unter

Written by Greg Wilson

2006/10/26 at 10:06

Posted in Community