SISO (Single Input Single Output) method (default)

H₀(s) is calculated as a rational function expressed as a sum of partial fractions.

$H_n\left(s\right)={\sum }_{k=1}^N\frac{r_{n,k}}{s-p_k}+D_n$

where r_n,k : residues , p_k : system poles , D_n : direct gain of H(s)

The algorithm, numerically well-conditioned for high-frequency and large band applications, allows the control of the undesired effects of over-modeling through a systematic approach with the aid of a new analysis parameter, ρ, extracted from a residue analysis. From the residues, and taking into account the resonance frequency, the normalized factor ρ_i,k is defined as in the equation below.

Residue analysis : ${\rho }_{i,k}=\frac{\left|H^{i,k}\left(j{\omega }_r\right)\right|}{\left|H^i\left(j{\omega }_r\right)\right|-\left|H^{i,k}\left(j{\omega }_r\right)\right|}$ $$

With : ω_r : resonance frequency

The residue obtained at a sensitive node have large values, while the residues corresponding to pole-zero quasi-constellations identified at a node with poor observability are very small.