@Test
public void testClosestToUpperBound() {

    assertEquals(1.3, SpikeInterpolation.getUpperValue(useAr, 1.3), 1e-8);
    assertEquals(2, SpikeInterpolation.getUpperValue(useAr, 1.9), 1e-8);
    assertEquals(2.9, SpikeInterpolation.getUpperValue(useAr, 2.7), 1e-8);
    assertEquals(2.9, SpikeInterpolation.getUpperValue(useAr, 2.9), 1e-8);
}