Singular values after formula_58, which are below the filtering threshold, are set to zero; for an arbitrary singular value formula_60, the threshold is denoted by the following formula:  formula_62 and are the maximum singular value and significant decimal digits, respectively. For a data with significant digits accurate up to , singular values below formula_63 are considered noise.  formula_64 and formula_65 are obtained through removing the last and first row and column of the filtered matrix formula_66, respectively; formula_58 columns of formula_55 represent formula_69. Filtered formula_42 and formula_43 matrices are obtained as:  Prefiltering can be used to combat noise and enhance signal-to-noise ratio (SNR). Band-pass matrix pencil (BPMP) method is a modification of the GPOF method via FIR or IIR band-pass filters. GPOF can handle up to 25 dB SNR. For GPOF, as well as for BPMP, variace of the estimates approximately reaches Cramér–Rao bound. Residues of the complex poles are obtained through the least squares problem:  The method is generally used for the evaluation of Sommerfeld integrals in discrete complex image method for method of moments, where the spectral Green's function is approximated as a sum of complex exponentials. Additionally, the method is used in antenna analysis, S-parameter-estimation in microwave integrated circuits, wave propagation analysis, moving target indication and radar signal processing.