<t>Just did an eigenvalue decomposition of that correlation matrix and there are two negative eigenvalues (which is why the determinant is positive). So it's not positive definite.> cormat [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [1,] 1.000 0.290 0.811 0.422 0.849 0.688 0.788 0.810 0.846 [2,] 0....