lasp/cpp_src/dsp/lasp_window.cpp

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// lasp_window.cpp
//
// Author: J.A. de Jong - ASCEE
//
/* #define DEBUGTRACE_ENABLED */
#include "debugtrace.hpp"
#include "lasp_window.h"
using rte = std::runtime_error;
using std::cerr;
using std::endl;
// Safe some typing. Linspace form 0 up to (and NOT including N).
#define lin0N arma::linspace(0, N - 1, N)
vd Window::hann(const us N) {
return arma::pow(arma::sin((arma::datum::pi/N) * lin0N), 2);
}
vd Window::hamming(const us N) {
d alpha = 25.0 / 46.0;
return alpha - (1 - alpha) * arma::cos(2 * number_pi * lin0N / N);
}
vd Window::blackman(const us N) {
d a0 = 7938. / 18608.;
d a1 = 9240. / 18608.;
d a2 = 1430. / 18608.;
return a0 - a1 * d_cos((2 * number_pi/N) * lin0N) +
a2 * d_cos((4 * number_pi / N)* lin0N );
}
vd Window::rectangular(const us N) { return arma::ones(N); }
vd Window::bartlett(const us N) {
return 1 - arma::abs(2 * (lin0N - (N - 1) / 2.) / N);
}
vd Window::create(const WindowType w, const us N) {
switch (w) {
case WindowType::Hann: {
return hann(N);
break;
}
case WindowType::Hamming: {
return hamming(N);
break;
}
case WindowType::Rectangular: {
return rectangular(N);
break;
}
case WindowType::Bartlett: {
return bartlett(N);
break;
}
case WindowType::Blackman: {
return blackman(N);
break;
}
default:
abort();
break;
}
}