<t>Changing eigenvales is also feasible (maybe easier since the constrains are each bigger than 0 and sum equal to n).For a trivariate, suppose the upper triangle is 0.5,0.8, -0.1. The eigenvalues are 1.90, 1.09 and 0.01.Now slightly changing them to 1.95, 1.04 and 0.01, you get a new correlation ma...