DIAGNOSTIC SYSTEM

In a diagnostic system, output patterns stored in first and second memories are compared by a comparing device so as to get remainders of items known by comparing the output patterns. The remainders of the items are shown as a graph of an interrelationship between the items by an output device. An operator can know mutual affect of the items and tendency of a machine by watching the graph. Therefore, trouble relating to the items, which interact mutually, can be prevented, and a suitable counteraction can be quickly taken even after trouble occurs, so that the maintenance efficiency can be greatly increased.