1. A method for characterizing an input signal, the method comprising the steps of: providing an input signal to at least one input node of a computing reservoir by supplying at least one photonic wave to the at least one input node and by temporally encoding the input signal by modulating the at least one photonic wave as function of the input signal, propagating said at least one photonic wave via passive guided or unguided propagation between discrete nodes of said computing reservoir, each discrete node being adapted for passively relaying the at least one photonic wave over the passive interconnections connected thereto, obtaining a plurality of readout signals, in which each readout signal is determined by a non-linear relation to the at least one photonic wave in at least one readout node of said computing reservoir, and combining said plurality of readout signals into an output signal, said combining taking into account a plurality of training parameters.