auto_correlate()

MAYAFLUX_API std::vector< double > MayaFlux::Kinesis::Discrete::auto_correlate	(	std::span< const double >	src,
		bool	normalize = true
	)

Auto-correlation via FFT.

Parameters

src	Input signal
normalize	Normalise result to zero-lag peak

Returns

Auto-correlation, same length as src

Definition at line 139 of file Convolution.cpp.

{
    auto out = apply_convolution(src, src,
        [](const auto& s, const auto&, auto& r) {
            std::transform(std::execution::par_unseq, s.begin(), s.end(), s.begin(), r.begin(),
                [](const std::complex<double>& a, const std::complex<double>& b) {
                    return a * std::conj(b);
                });
        });
 
    if (normalize && !out.empty()) {
        const double peak = *std::max_element(out.begin(), out.end());
        if (peak > 0.0) {
            std::transform(std::execution::par_unseq, out.begin(), out.end(), out.begin(),
                [peak](double v) { return v / peak; });
        }
    }
 
    return out;
}

References a, apply_convolution(), auto_correlate(), b, normalize(), out, peak(), and src.

Referenced by auto_correlate(), and MayaFlux::Yantra::ConvolutionTransformer< InputType, OutputType >::transform_implementation().

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