In the last decades, there has been an increasing interest on semistate models based on differential- algebraic equations (DAEs) for the analysis and simulation of non-linear electrical circuits. In the DAE context, the index of a semistate model becomes a standard measure for the analytical and numerical difficulties faced in simulations. This book presents a tree-based index calculation that extends previous results for passive circuits, making it possible to characterize the index of uncoupled circuits including both passive an active devices. Our results focus mainly on the augmented...