From: Brian Teague (
Date: Thu Oct 16 2008 - 18:27:10 CDT

Dear tutorials-l

I'm writing to comment on the sculptor.tcl file included with the files
for step 5 of the bionanotechnology tutorial. I was using it to bend
some DNA for an illustration I was creating and noticed that after
running sculptor.tcl, the resulting molecule's helix had the wrong
handedness (it was left-handed instead of right-handed.)

I am no TCL expert, and don't even pretend to understand the vector math
involved. The attached diff is completely inelegant, but it does
produce the correct results - ie, the molecule is curved correctly, and
maintains its right-handed helix. Perhaps whoever is maintaining the
bionanotech tutorial can figure out what the "right" fix is instead.


Brian Teague
The Laboratory for Molecular and Computational Genomics
If you're coasting, you're going downhill.
               -- L. W. Pierson

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