def METHOD_NAME(variant_scalar_rgb):
    assert(dr.allclose(mi.warp.square_to_std_normal_pdf([0, 0]),   0.16, atol=1e-2))
    assert(dr.allclose(mi.warp.square_to_std_normal_pdf([0, 0.8]), 0.12, atol=1e-2))
    assert(dr.allclose(mi.warp.square_to_std_normal_pdf([0.8, 0]), 0.12, atol=1e-2))