Glossary of Symbols
| a, b | Sample regression coefficients, arbitrary constants |
| A | Amplitude, reverse arrangements, regression coefficient |
| A(f) | Frequency response function after linear or nonlinear operation |
| b[] | Bias error of [] |
| B | Cyclical frequency bandwidth, regression coefficient |
| Be | Frequency resolution bandwidth |
| Bn | Noise spectral bandwidth |
| Bs | Statistical bandwidth |
| c | Mechanical damping coefficient, arbitrary constant |
| C | Electrical capacitance |
| Cxy | Covariance |
| Cxx(τ) | Autocovariance function |
| Cxy(τ) | Cross-covariance function |
| Cxy(f) | Coincident spectral density function (one-sided) |
| e(t) | Potential difference |
| E[] | Expected value of [] |
| f | Cyclical frequency |
 f | Bandwidth resolution (Hz) |
 | Fourier transform of [] |
| Gxx(f) | Autospectral density function (one-sided) |
| Gxy(f) | Cross-spectral density function (one-sided) |
| Gyy·x(f) | Conditioned autospectral density function (one-sided) |
| Gxiy·xj(f) | Conditioned cross-spectral density function (one-sided) |
| G(k) | Wavenumber spectral density function (one-sided) |
 | “Energy” spectral density function |
| h(τ) | Unit impulse response function |
| H(f) | Frequency response function |
| |H(f)| | System gain factor |
 | Hilbert ... |
