Hi Yen, It is simply a calculation of principal axes where atoms are mass-weighted points, see: <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/measure.html#inertia> I doubt someone would publish a paper about such a fundamental calculation, so although I did not read the J Mol Graph paper, it is likely to be a different method. The person who wrote the "measure inertia" code is away currently, but if there is anything else to say, he may send another reply later. Best, Elaine ---------- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco On Jan 24, 2013, at 1:07 PM, Yen-Ting Lai wrote:
Hi, What's the formula that's used by "measure inertia"? I found a paper: An ellipsoidal approximation of protein shape. J. Mol Graph (1983) Does the "measure inertia" use the same method? Thank you! Yen