Program: mat_diag, p, EIG_VAL= eig_val, EIG_VEC= eig_vec INPUT: p 6-element vector [Pxx, Pyy, Pzz, Pxy, Pxz, Pyz] of a symmetric matrix OUTPUT: eig_val, eig_vec PURPOSE: Diagonalize a 3x3 symmetric matrix Returns the eigenvalues and eigenvectors. The eigenvalues are the diagnonal elements of the matrix The eigenvectors are the associated principle axis. NOTES: The first eigenvalue (eig_val(0)) and eigenvector (eig_vec(*,0)) are the distinguisheable eigenvalue and the major (symmetry) axis, respectively. The "degenerate" eigenvalues are sorted such that the 2nd eigenvalue is smaller than the third one. CREATED BY: Tai Phan (95-9-15) LAST MODIFICATION: 95-9-29 Tai Phan