[gmx-users] principal components

Nguyen Hoang Phuong phuong at theochem.uni-frankfurt.de
Tue Apr 9 11:28:52 CEST 2002

Dear All,

I have tried to calculate the projections of a trajectory on
eigenvectors. My program and g_covar give the same value of the
eigenvalues of the covariance matrix. However, my principal components
have different sign with those from g_anaeig. In my calculation of the
eigenvectors, the eigenvalues and the projections, I did not fit
the structures to a reference structure. According to g_anaeig, all
structures are fitted to the structure in the eigenvector file. I'm
wondering that causes the different sign in the pc's?   


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