Fast DC analysis and its application to combinatorial optimization problems

Many combinatorial optimization problems such as the min cost flow problem are equivalent to the solution of appropriate DC circuits made up of positive resistors, voltage sources, current sources and ideal diodes. Simulating the DC circuit is an alternative approach to the approximate solution of such problems. However, conventional simulators such as SPICE are too slow for this purpose. This paper describes the structure and performance of a fast DC analyzer built at EE department, IIT Bombay specifically for solving large circuits consisting of positive resistors, voltage sources, current sources and diodes. Using the simulator, we have analyzed circuits composed of diodes, positive resistors, current and voltage sources of size up to 700,000 nodes and 1.2 million edges on a 3.0 GHz, 1GB RAM, PIV processor in at most 1.2 hrs. We also report a comparative study of the performance of our DC analyzer with that of fastest commercial simulator.