We continue the work from Tan and Vandewalle (1987), Malabre and Velasquez (1994), and Bonilla Estrada and Malabre (2000) and study the row-by-row decoupling problem of linear time-invariant systems by proportional and derivative state feedback. Our contribution, with respect to previous results, is that we develop a numerical method to compute the desired feedback matrices. Our method is only based on orthogonal transformations and hence is numerically reliable. A numerical example is given to illustrate the proposed method.