Adds the upcrossing analysis functions in MATLAB

mhkit/tests/upcrossing_Test.m

@@ -0,0 +1,176 @@
+classdef upcrossing_Test < matlab.unittest.TestCase
+    properties
+        t
+        signal
+        zeroCrossApprox
+    end
+
+    methods (TestClassSetup)
+        % Shared setup for the entire test class
+        function setupTestClass(testCase)
+            % Define time vector
+            testCase.t = linspace(0, 4, 1000);
+
+            % Define signal
+            testCase.signal = testCase.exampleWaveform_(testCase.t);
+
+            % Approximate zero crossings
+            testCase.zeroCrossApprox = [0, 2.1, 3, 3.8];
+        end
+
+    end
+
+    methods (TestMethodSetup)
+        % Setup for each test
+    end
+
+    % methods (Test)
+    %     % Test methods
+    %
+    %     function unimplementedTest(testCase)
+    %         testCase.verifyFail("Unimplemented test");
+    %     end
+    % end
+
+    methods
+        function signal = exampleWaveform_(~, t)
+            % Generate a simple waveform form to analyse
+            % This has been created to perform
+            % a simple independent calcuation that
+            % the mhkit functions can be tested against.
+            A = [0.5, 0.6, 0.3];
+            T = [3, 2, 1];
+            w = 2 * pi ./ T;
+
+            signal = zeros(size(t));
+            for i = 1:length(A)
+                signal = signal + A(i) * sin(w(i) * t);
+            end
+        end
+
+        function [crests, troughs, heights, periods] = exampleAnalysis_(testCase, signal)
+            % NB: This only works due to the construction
+            % of our test signal. It is not suitable as
+            % a general approach.
+
+            % Gradient-based turning point analysis
+            grad = diff(signal);
+
+            % +1 to get the index at turning point
+            turningPoints = find(grad(1:end-1) .* grad(2:end) < 0) + 1;
+
+            crestInds = turningPoints(signal(turningPoints) > 0);
+            troughInds = turningPoints(signal(turningPoints) < 0);
+
+            crests = signal(crestInds);
+            troughs = signal(troughInds);
+            heights = crests - troughs;
+
+            % Numerical zero-crossing solution
+            zeroCross = zeros(size(testCase.zeroCrossApprox));
+            for i = 1:length(testCase.zeroCrossApprox)
+                zeroCross(i) = fzero(@(x) testCase.exampleWaveform_(x), ...
+                    testCase.zeroCrossApprox(i));
+            end
+
+            periods = diff(zeroCross);
+        end
+    end
+
+    methods (Test)
+        %% Test functions without indices (inds)
+        function test_peaks(testCase)
+            [want, ~, ~, ~] = testCase.exampleAnalysis_(testCase.signal);
+            got = uc_peaks(testCase.t, testCase.signal);
+
+            testCase.verifyEqual(got, want, 'AbsTol', 1e-3);
+        end
+
+        function test_troughs(testCase)
+            [~, want, ~, ~] = testCase.exampleAnalysis_(testCase.signal);
+            got = uc_troughs(testCase.t, testCase.signal);
+
+            testCase.verifyEqual(got, want, 'AbsTol', 1e-3);
+        end
+
+        function test_heights(testCase)
+            [~, ~, want, ~] = testCase.exampleAnalysis_(testCase.signal);
+
+            got = uc_heights(testCase.t, testCase.signal);
+
+            testCase.verifyEqual(got, want, 'AbsTol', 1e-3);
+        end
+
+        function test_periods(testCase)
+            [~, ~, ~, want] = testCase.exampleAnalysis_(testCase.signal);
+
+            got = uc_periods(testCase.t, testCase.signal);
+
+            testCase.verifyEqual(got, want, 'AbsTol', 2e-3);
+        end
+
+        function test_custom(testCase)
+            [want, ~, ~, ~] = testCase.exampleAnalysis_(testCase.signal);
+
+            % create a similar function to finding the peaks
+            f = @(ind1, ind2) max(testCase.signal(ind1:ind2));
+
+            got = uc_custom(testCase.t, testCase.signal, f);
+
+            testCase.verifyEqual(got, want, 'AbsTol', 1e-3);
+        end
+
+        %% Test functions with indcies
+        function test_peaks_with_inds(testCase)
+            [want, ~, ~, ~] = testCase.exampleAnalysis_(testCase.signal);
+
+            inds = upcrossing(testCase.t, testCase.signal);
+
+            got = uc_peaks(testCase.t, testCase.signal, inds);
+
+            testCase.verifyEqual(got, want, 'AbsTol', 1e-3);
+        end
+
+        function test_trough_with_inds(testCase)
+            [~, want, ~, ~] = testCase.exampleAnalysis_(testCase.signal);
+
+            inds = upcrossing(testCase.t, testCase.signal);
+
+            got = uc_troughs(testCase.t, testCase.signal, inds);
+
+            testCase.verifyEqual(got, want, 'AbsTol', 1e-3);
+        end
+
+        function test_heights_with_inds(testCase)
+            [~, ~, want, ~] = testCase.exampleAnalysis_(testCase.signal);
+
+            inds = upcrossing(testCase.t, testCase.signal);
+
+            got = uc_heights(testCase.t, testCase.signal, inds);
+
+            testCase.verifyEqual(got, want, 'AbsTol', 1e-3);
+        end
+
+        function test_periods_with_inds(testCase)
+            [~, ~, ~, want] = testCase.exampleAnalysis_(testCase.signal);
+            inds = upcrossing(testCase.t, testCase.signal);
+
+            got = uc_periods(testCase.t, testCase.signal,inds);
+
+            testCase.verifyEqual(got, want, 'AbsTol', 2e-3);
+        end
+
+        function test_custom_with_inds(testCase)
+            [want, ~, ~, ~] = testCase.exampleAnalysis_(testCase.signal);
+            inds = upcrossing(testCase.t, testCase.signal);
+
+            % create a similar function to finding the peaks
+            f = @(ind1, ind2) max(testCase.signal(ind1:ind2));
+
+            got = uc_custom(testCase.t, testCase.signal, f, inds);
+
+            testCase.verifyEqual(got, want, 'AbsTol', 1e-3);
+        end
+
+    end
+end