Abstract: A return route search device includes a starting point/destination point setting section which accepts the setting of a starting point on a circuit from which a return current starts accompanied by a signal transmission on the circuit, and a setting of a destination point on the circuit to which the current flows. The return route search device further includes an easiness setting section which accepts a setting of easiness of conduction of the return current through each of portions on the circuit, and a return route search section which searches for a route when the return current flows from the starting point to the destination point on the basis of the easiness of conduction on the circuit.

Abstract: This invention is directed to a method and apparatus to find out an optimum solution in automatic routing or automatic placement with certainty and at a high-speed to improve a routing rate, and to realize automatic routing in a high-density. To these end, a routing approach is selected in a conversational mode while routing efficiency is consulted to compose routing processing procedure so as to generate a routing program. Besides, component placement processing procedures designated according to placement control information are combined to generate the placement program. A straight line between component pins adjacent to each other is defined as a chord, a wave for maze method routing is generated from a start point toward an end point of a routing path and propagated between the chords adjacent to each other.