A new method for computing positive time-frequency distributions (TFDs) for nonstationary signals is presented. This work extends the earlier work of the author and his colleagues in computing positive TFDs [8,11]. This paper describes a general quadratic programming approach to the problem of computing these signal-dependent distributions. The method is based on an evolutionary spectrum formulation of positive TFDs. The minimization problem reduces to a linearly-constrained quadratic programming problem, for which standard solutions are widely available.