Testability is a very useful concept in the field of circuit testing and fault diagnosis and can be defined as a measure of the effectiveness of a selected test point set. A very efficient approach for automated testability evaluation of analog circuits is based on the use of symbolic techniques. Different algorithms relying on the symbolic approach have been presented in the past by the authors and in this work noteworthy improvements on these algorithms are proposed. The new theoretical approach and the description of the subsequent algorithm that optimizes the testability evaluation from a computational point of view are presented. As a result, in the computer implementation the roundoff errors are completely eliminated and the computing speed is increased. The program which implements this new algorithm is also presented.