Computer-program description. Root-locus plotting by digital computer using operational-array technique

The objective of the paper is to present a general program for computation of the root locus of time-invariant systems. The method adopted for root-locus location is to express the characteristic equation in polynomial form for every chosen value of the static-loop sensitivity; the factorisation then gives the location of the poles. In addition, the breakaway points are also individually computed and graphically superimposed on the already computed and plotted root-locus diagrams. The break points are where the locus departs from the real axis or returns to it; hence the terms breakaway and break-in points, respectively. In more general interpretation, the breakpoints are where two or more root-locus branches come into contact anywhere in the complex plane. The interpretation above is wholly implemented in the program.