### Question:
FilterTimeDomainResponseCalculator extends FilterResponseCalculator { public FilterTimeDomainResponse getStepResponse(int numberOfPoints) { double[] excitation = generateStepExcitation(numberOfPoints); double[] stepResponseAmplitudes = AbstractIIRSinglechannelSampleFilter.filter(filterCoefficients.getBCoefficients(), filterCoefficients.getACoefficients(), excitation); return new FilterTimeDomainResponse(stepResponseAmplitudes, samplingFrequency); } FilterTimeDomainResponseCalculator(double samplingFrequency, FilterCoefficients filterCoefficients); FilterTimeDomainResponse getStepResponse(int numberOfPoints); FilterTimeDomainResponse getImpulseResponse(int numberOfPoints);  }### Answer:
@Test public void testGetStepResponse() { checkStepResponse( new double[] {0.34,0.12, 0.6, 0.33}, new double[] {1, 0.4, 0.01, 0.02}, 128.0, new double[] { 0.3400, 0.3240, 0.9270, 1.0092, 0.9706, 0.9731, 0.9709, 0.9725, 0.9718, 0.9721, 0.9720, 0.9721, 0.9720 }); }