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Function iir_lowpass¶

`function` iir_lowpass(const zpk &, double, double) dsp ¶

zpk iir_lowpass(const zpk& filter, double frequency, double fs = 2.0)

Designs a digital lowpass IIR filter and returns ZPK coefficients.

Applies frequency pre-warping, lowpass-to-lowpass analog transformation, and bilinear transform to convert an analog lowpass prototype to a digital lowpass filter.Usage: iir_lowpass(butterworth(4), 1000, 48000) designs a 4th-order Butterworth lowpass at 1 kHz with 48 kHz sample rate.

Parameters
filter	Analog lowpass prototype (butterworth, chebyshev1, chebyshev2, bessel, or elliptic).
frequency	Cutoff frequency in Hz. If fs is omitted (left at its default of 2.0), frequency is interpreted as normalized to Nyquist, so the valid range is 0..1.
fs	Sampling frequency in Hz (default 2.0, i.e. Nyquist = 1 Hz).

Returns
	Digital lowpass filter in ZPK form.

Fully qualified name: kfr::iir_lowpass(const zpk &, double, double)

Declared at dsp/iir_design.hpp:261

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