### Question:
InitialStateCalculator { public double[] getInitialState() { return initialState; } InitialStateCalculator(FilterCoefficients filterCoefficients); double[] getInitialState(); double[] growSignal(double[] signal); double[] growSignal(double[] signal, boolean leftOnly);  }### Answer:
@Test public void testGetInitialState() { InitialStateCalculator calculator = new InitialStateCalculator(getSampleFilterCoefficients1()); double[] actual = calculator.getInitialState(); double[] expected = new double[] {0.99958345, -1.68782358, 0.73058189}; assertArrayEquals(expected, actual, 1e-4); calculator = new InitialStateCalculator(getSampleFilterCoefficients2()); actual = calculator.getInitialState(); expected = new double[] {3.17868852, 3.13934426, 1.2, 1.1, 0.4}; assertArrayEquals(expected, actual, 1e-4); }