A fault tree data array converts the logic of a fault tree into software by sing a data base technique. Each array element of a data array contains a decision or termination of the fault tree, and a relative exponential addressing expression provides the data elements with a unique position in the array. The next position in the data array to be examined is calculated by the relative exponential addressing expressions. For unsymmetrical fault trees on additional data array is generated to provide a sequential list of tests to be examined until a fault is found. Then the relative exponential addressing technique is used. The result is a more compact method of storing data in computer memory, hence providing an efficient method for implementing fault trees into software.