“…Most of these methods successfully solve the unconstrained problem, but the presence of, for example, state variable inequality constraints (SVIC) often resulted in both analytical and computational difficulties. Theoretical aspects of the SVIC problem have been studied by Berkovitz (1961), Dreyfus (1962), Chang (1962), Berkovitz and Dreyfus (1965) and Speyer and Bryson (1968), while early contributions to the numerical computation were due to Dreyfus (1962), Kelley (1962), Bryson and Denham (1964), McGill (1965), Lasdon et al (1967), Jacobson and Lele (1969), Mehra and Davis (1972), Neuman and Sen (1973) and Maurer and Gillessen (1975). The approaches of Dreyfus (1962) and Bryson and Denham (1964) require guesses for both the number and location of the junction points between constrained and unconstrained arcs.…”