1. A method of simulating a circuit, comprising: reading a description of the circuit that includes a list of components in the circuit and the interconnections between the components, the circuit including both a first set of nodes and components responsive to time-domain signals, including analog signals that are not modulated, and a second set of nodes and components responsive to time-frequency domain signals, which include RF signals, which are modulated; and in a single simulation flow, simulating the time-domain signals, which are not modulated, on the first set of nodes using a first set of non-linear equations and simulating the time-frequency domain signals, which are modulated, on the second set of nodes using a second set of non-linear equations; the single simulation flow including interrelately solving the first set of non-linear equations, and the second set of non-linear equations, until convergence, wherein the time-domain signals are analog signals included in at least one analog partition and the time-frequency domain signals are RF signals included in at least one RF partition and wherein a solution for simulation of the analog partition affects a solution for simulation of the RF partition.