@Test
public void testCalculateRayleighCrossSection() {

    double[] sectionSigma = algo.getCrossSection(new double[]{1., 2.});
    assertEquals(2, sectionSigma.length);
    assertEquals(1.004158010817489E-9, sectionSigma[0], 1e-8);
    assertEquals(3.9154039638717356E-12, sectionSigma[1], 1e-8);
}