def METHOD_NAME(variant_scalar_rgb):
    from mitsuba import spline
    assert dr.allclose(spline.eval_spline_d(0, 0, 0, 0, 0),   (0.0, 0.0))
    assert dr.allclose(spline.eval_spline_d(0, 0, 0, 0, 0.5), (0.0, 0.0))
    assert dr.allclose(spline.eval_spline_d(0, 0, 0, 0, 1),   (0.0, 0.0))
    assert dr.allclose(spline.eval_spline_d(0, 1, 1, 1, 1),   (1.0, 1.0))
    assert dr.allclose(spline.eval_spline_d(0, 1, 1, 1, 0),   (0.0, 1.0))
    assert dr.allclose(spline.eval_spline_d(0, 1, 1, 1, 0.5), (0.5, 1.0))
    assert dr.allclose(spline.eval_spline_d(0, 0, 1, -1, 0.5)[1], 0.0)