comparison tests/TestFiltFilt.cpp @ 506:285f18c0992a

Tests and fixes for FiltFilt: Fix overrun; reset filter between forwards and backwards processes

+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+#include "dsp/signalconditioning/FiltFilt.h"
+
+#define BOOST_TEST_DYN_LINK
+#define BOOST_TEST_MAIN
+
+#include <boost/test/unit_test.hpp>
+
+#include <stdexcept>
+
+using namespace std;
+
+BOOST_AUTO_TEST_SUITE(TestFiltFilt)
+
+// Our FiltFilt is, apparently intentionally (?) a bit different from
+// the equivalents in MATLAB and Octave (which themselves also differ)
+// in how it handles transients at either end. While the three should
+// all be "roughly" the same, all produce slightly different values.
+// So the "expected" values here are, unfortunately, simply produced
+// by the function itself, in a process involving tracing the values
+// passed in to each of the filter stages within it and compared their
+// outputs against MATLAB.
+
+static vector<double> iir_a { 1,5.75501989315662,16.326056867468,28.779190797823,34.2874379215653,28.137815126537,15.6064643257793,5.37874515231553,0.913800050254382,0.0,0.0 };
+static vector<double> iir_b { 0.0031954608137085,0.0180937089815597,0.0508407778575426,0.0895040074158415,0.107385387168148,0.0895040074158415,0.0508407778575426,0.0180937089815597,0.0031954608137085,0.0,0.0 };
+
+BOOST_AUTO_TEST_CASE(long_zeroes)
+{
+    vector<double> a(iir_a);
+    vector<double> b(iir_b);
+
+    vector<double> zeroes(1000, 0.0);
+    vector<double> expected(zeroes);
+
+    FiltFilt f({ a, b });
+    
+    int n = expected.size();
+    vector<double> out(n, 0.0);
+
+    f.process(zeroes.data(), out.data(), n);
+    
+    double thresh = 1e-12;
+    
+    for (int i = 0; i < n; ++i) {
+	BOOST_CHECK_SMALL(out[i] - expected[i], thresh);
+    }
+}
+
+BOOST_AUTO_TEST_CASE(empty)
+{
+    vector<double> a(iir_a);
+    vector<double> b(iir_b);
+    vector<double> in;
+    vector<double> out;
+    vector<double> expected;
+
+    FiltFilt f({ a, b });
+
+    f.process(in.data(), out.data(), 0);
+}
+
+BOOST_AUTO_TEST_CASE(single_value)
+{
+    vector<double> a(iir_a);
+    vector<double> b(iir_b);
+    vector<double> in({ 1.0 });
+    vector<double> out({ 0.0 });
+    vector<double> expected({ -0.000236642942007 });
+
+    FiltFilt f({ a, b });
+
+    f.process(in.data(), out.data(), 1);
+
+    double thresh = 1e-12;
+
+    BOOST_CHECK_SMALL(out[0] - expected[0], thresh);
+}
+
+BOOST_AUTO_TEST_CASE(shortish)
+{
+    vector<double> a(iir_a);
+    vector<double> b(iir_b);
+
+    vector<double> in { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
+    vector<double> expected { 0.0180395628158, -0.0317213769922, 0.0276928584707, -0.00944844359572, -0.0119394068579, 0.0252763627734, -0.0239770024451, 0.010560830803, 0.00726290602379, -0.0191915890394, 0.0202451156989, -0.0103434265023, -0.00341952789985, 0.0142823904341, -0.0160627659442, 0.00984876782803 };
+
+    FiltFilt f({ a, b });
+    
+    int n = expected.size();
+    vector<double> out(n, 0.0);
+
+    f.process(in.data(), out.data(), n);
+    
+    double thresh = 1e-12;
+    
+    for (int i = 0; i < n; ++i) {
+	BOOST_CHECK_SMALL(out[i] - expected[i], thresh);
+    }
+}
+
+BOOST_AUTO_TEST_SUITE_END()