Bugs item #3260566, was opened at 2011-03-30 11:54 Message generated for change (Tracker Item Submitted) made by ksdrew You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=428740&aid=3260566&group_id=40728
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Library Functions Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: ksdrew (ksdrew) Assigned to: Nobody/Anonymous (nobody) Summary: precision error in conversion from internal coordiantes Initial Comment: Name: Kevin Drew Email: kd...@nyu.edu Version: openbabel-2.3.0 OS: Mac and Linux I noticed a small change in torsion angle degrees when I input gzmat formatted files (internal coordinates). I only notice it with torsion angles of 0.0 (d5 and d6 in sample) and 180.0 (d9 in sample). The roundtrip conversion returns values of 0.03 (rather than 0.0) and 179.97 (rather than 180.0) respectively. --command-- obabel -i "gzmat" sample.gzmat -O output.gzmat --command-- The problem seems to be related to the boundary conditions of an acos call in the vectorAngle function in math/vector3.cpp. I have increased the precision of boundary condition tests at lines 211 and 214 of math/vector3.cpp on my local copy and it seems to produce the desired results. -snip- 211 if (dp < -0.99999999999999) 212 return 180.0 213 214 if (dp > 0.99999999999999) 215 return 0.0 -snip- I am not sure if this is the best way to fix this and I am not sure if this fixes all cases. Also, it seems like the vectorAngle function is deemed deprecated by comments in the code but is still being called by the CalcTorsionAngle function in math/vector3.cpp. Please let me know if you need any more information. Thank you for your time, Kevin Drew ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=428740&aid=3260566&group_id=40728 ------------------------------------------------------------------------------ Create and publish websites with WebMatrix Use the most popular FREE web apps or write code yourself; WebMatrix provides all the features you need to develop and publish your website. http://p.sf.net/sfu/ms-webmatrix-sf _______________________________________________ OpenBabel-Devel mailing list OpenBabel-Devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openbabel-devel
