  This paper presents a new numerical approach to the study of non-periodicity
in signals, which can complement the maximal Lyapunov exponent method for
determining chaos transitions of a given dynamical system. The proposed
technique is based on the continuous wavelet transform and the wavelet
multiresolution analysis. A new parameter, the \textit{scale index}, is
introduced and interpreted as a measure of the degree of the signal's
non-periodicity. This methodology is successfully applied to three classical
dynamical systems: the Bonhoeffer-van der Pol oscillator, the logistic map, and
the Henon map.
