Function spectrogram_normalized 

pub fn spectrogram_normalized<T>(
    x: &[T],
    fs: Option<f64>,
    nperseg: Option<usize>,
    noverlap: Option<usize>,
    db_range: Option<f64>,
) -> FFTResult<(Vec<f64>, Vec<f64>, Array2<f64>)>
where
    T: NumCast + Copy + Debug,

Compute a normalized spectrogram suitable for display as a heatmap.

This is a convenience function that computes a spectrogram and normalizes its values to a range suitable for visualization. It also applies a logarithmic scaling to better visualize the dynamic range of the signal.

Arguments

• x - Input signal array
• fs - Sampling frequency of the signal (default: 1.0)
• nperseg - Length of each segment (default: 256)
• noverlap - Number of points to overlap between segments (default: nperseg // 2)
• db_range - Dynamic range in dB for normalization (default: 80.0)

Returns

• A tuple containing:
  • Frequencies vector (f)
  • Time vector (t)
  • Normalized spectrogram result matrix (Sxx_norm) with values in [0, 1]

Errors

Returns an error if the computation fails or if parameters are invalid.

Examples

use scirs2_fft::spectrogram_normalized;
use std::f64::consts::PI;

// Generate a chirp signal
let fs = 1000.0; // 1 kHz sampling rate
let time = (0..1000).map(|i| i as f64 / fs).collect::<Vec<_>>();
let chirp = time.iter().map(|&ti| (2.0 * PI * (10.0 + 50.0 * ti) * ti).sin()).collect::<Vec<_>>();

// Compute normalized spectrogram
let (f, t, sxx_norm) = spectrogram_normalized(
    &chirp,
    Some(fs),
    Some(128),
    Some(64),
    Some(80.0),
).unwrap();

// Values should be normalized to [0, 1]
for row in sxx_norm.axis_iter(scirs2_core::ndarray::Axis(0)) {
    for &val in row {
        assert!((0.0..=1.0).contains(&val));
    }
}