From chemistry-request@server.ccl.net Thu Feb 28 19:51:50 2002 Received: from mole.chem.iupui.edu ([134.68.136.192]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id g210po512210 for ; Thu, 28 Feb 2002 19:51:50 -0500 Received: from mole.chem.iupui.edu (mole.chem.iupui.edu [134.68.136.192]) by mole.chem.iupui.edu (8.9.1/8.9.1) with ESMTP id TAA318416; Thu, 28 Feb 2002 19:49:46 -0500 (EST) Date: Thu, 28 Feb 2002 19:49:45 -0500 From: Daquan Gao To: Ingo Brunberg cc: alogean@aspirine.u-strasbg.fr, chemistry@ccl.net Subject: Re: CCL:A little geometrical problem In-Reply-To: <200203010206.DAA15091@oc30.uni-paderborn.de> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII That is about right. The condition No. 2) leads to inifinitely many solutions.... The points of possible CB forms a circle. By the way, the only anlges that satifsy this condition are: N-CA-C=180 ! Daquan On Fri, 1 Mar 2002, Ingo Brunberg wrote: > Obviously this problem is not as trivial as it seems. Though I can > think of a rather complicated solution, I just want to point out, that > there is most likely no single solution. The point you are searching > is located on the intersection of two cones with the angles N-CA-CB > and C-CA-CB originating from CA. So there are three different cases: > > 1) N-CA-CB + C-CA-CB < N-CA-C: no solution > 2) N-CA-CB + C-CA-CB = N-CA-C: one solution > 3) N-CA-CB + C-CA-CB > N-CA-C: two solutions > > Seems like the problem leads to a quadratic equation. > > Regards, > > Ingo > > > A little geometrical problem : > > > > Taken a residue in a PDB file, how can I calculate the Cartesian > > coordinates of CB when I know the coordinates of N, CA and C, the angle > > N-CA-CB, C-CA-CB and the bond length CA-CB ? > > > > It seems to be trivial but I am unable to find a solution ! > > > > I am sure that somebody can help me. > > > > In advance thank you > > > > LOGEAN Antoine > > -= This is automatically added to each message by mailing script =- > CHEMISTRY@ccl.net -- To Everybody | CHEMISTRY-REQUEST@ccl.net -- To Admins > MAILSERV@ccl.net -- HELP CHEMISTRY or HELP SEARCH > CHEMISTRY-SEARCH@ccl.net -- archive search | Gopher: gopher.ccl.net 70 > Ftp: ftp.ccl.net | WWW: http://www.ccl.net/chemistry/ | Jan: jkl@ccl.net > > > > >