#include <envelopes.h>

Detailed Description

template<typename Sample = double>
class signalsmith::envelopes::BoxStackFilter< Sample >

FIR filter made from a stack of BoxFilters.

This filter has a non-negative impulse (monotonic step response), making it useful for smoothing positive-only values. It provides an optimal set of box-lengths, chosen to minimise peaks in the stop-band:

Impulse responses for various stack sizes at length N=1000

Since the underlying box-averages must have integer width, the peaks are slightly higher for shorter lengths with higher numbers of layers:

Frequency responses for various stack sizes at length N=30

Static Methods
static std::vector< double >	optimalRatios (int layerCount)
	Returns an optimal set of length ratios (heuristic for larger depths)

static constexpr double	layersToBandwidth (int layers)
	Approximate (optimal) bandwidth for a given number of layers.

static constexpr double	layersToPeakDb (int layers)
	Approximate (optimal) peak in the stop-band.

Methods
	BoxStackFilter (int maxSize, int layers=4)

void	resize (int maxSize, int layerCount)
	Sets size using an optimal (heuristic at larger sizes) set of length ratios.

template<class List>
auto	resize (int maxSize, List ratios) -> decltype(void(std::begin(ratios)), void(std::end(ratios)))
	Sets the maximum (and current) impulse response length and explicit length ratios.

void	resize (int maxSize, std::initializer_list< double > ratios)

void	set (int size)
	Sets the impulse response length (does not reset if `size` ≤ `maxSize`)

void	reset (Sample fill=Sample())
	Resets the filter.

Sample	operator() (Sample v)