1. A non-transitory computer-readable medium storing instructions, the instructions comprising: one or more instructions that, when executed by one or more processors, cause the one or more processors to: identify a linear time invariant system including at least one delay; determine a representation of the linear time invariant system in a state-space form, the representation including a set of state-space equations that define: a state derivative based on a weighted sum of: state variables without the at least one delay, system input variables without the at least one delay, and internal delay output variables; system output variables based on a weighted sum of: the state variables without the at least one delay, the system input variables without the at least one delay, and the internal delay output variables; internal delay input variables based on a weighted sum of: the state variables without the at least one delay, the system input variables without the at least one delay, and the internal delay output variables; and internal delay output variables as the internal delay input variables delayed by an amount corresponding to the at least one delay; generate, based on the representation, a model of the linear time invariant system, the model of the linear time invariant system including: a delay free linear time invariant model, and a bank of delays; determine, based on the model of the linear time invariant system, changes in a signal of the model of the linear time invariant system; determine a change in magnitude of a first set of the changes in the signal; determine an area between successive changes of the changes in the signal; approximate a portion of a second set of the changes in the signal; determine, based on the area between the successive changes and approximating the portion of the second set of the changes in the signal, a time domain response of the model of the linear time invariant system; determine, based on evaluating the delay free linear time invariant model and the bank of delays at a plurality of frequency points, a frequency domain response of the linear time invariant system; evaluating the bank of delays being performed separately with respect to evaluating the delay free linear time invariant model; and output a result indicating the frequency domain response and the time domain response of the linear time invariant system.