pub fn instantaneous_frequency(z: &[Complex64], fs: f64) -> Vec<f64>Expand description
Instantaneous frequency in Hz from an analytic signal: centred difference of the unwrapped
phase, (φ[n+1] − φ[n−1]) · fs / 4π; at each end, the slope of a line through 3 points (the
same estimator as a 3-point Savitzky-Golay derivative). Phase steps are taken one sample at
a time, so frequencies up to Nyquist are estimated without wrapping.