def arc_by_radian(x, y, height, radian_range, thickness, gaussian_width):
    """
    Radial arc with Gaussian fall-off after the solid ring-shaped
    region with the given thickness, with shape specified by the
    (start,end) radian_range.
    """

    # Create a circular ring (copied from the ring function)
    radius = height/2.0
    half_thickness = thickness/2.0

    distance_from_origin = np.sqrt(x**2+y**2)
    distance_outside_outer_disk = distance_from_origin - radius - half_thickness
    distance_inside_inner_disk = radius - half_thickness - distance_from_origin

    ring = 1.0-np.bitwise_xor(np.greater_equal(distance_inside_inner_disk,0.0),
                              np.greater_equal(distance_outside_outer_disk,0.0))

    sigmasq = gaussian_width*gaussian_width

    if sigmasq==0.0:
        inner_falloff = x*0.0
        outer_falloff = x*0.0
    else:
        with float_error_ignore():
            inner_falloff = np.exp(np.divide(-distance_inside_inner_disk*distance_inside_inner_disk, 2.0*sigmasq))
            outer_falloff = np.exp(np.divide(-distance_outside_outer_disk*distance_outside_outer_disk, 2.0*sigmasq))

    output_ring = np.maximum(inner_falloff,np.maximum(outer_falloff,ring))

    # Calculate radians (in 4 phases) and cut according to the set range)

    # RZHACKALERT:
    # Function float_error_ignore() cannot catch the exception when
    # both np.dividend and divisor are 0.0, and when only divisor is 0.0
    # it returns 'Inf' rather than 0.0. In x, y and
    # distance_from_origin, only one point in distance_from_origin can
    # be 0.0 (circle center) and in this point x and y must be 0.0 as
    # well. So here is a hack to avoid the 'invalid value encountered
    # in divide' error by turning 0.0 to 1e-5 in distance_from_origin.
    distance_from_origin += np.where(distance_from_origin == 0.0, 1e-5, 0)

    with float_error_ignore():
        sines = np.divide(y, distance_from_origin)
        cosines = np.divide(x, distance_from_origin)
        arcsines = np.arcsin(sines)

    phase_1 = np.where(np.logical_and(sines >= 0, cosines >= 0), 2*pi-arcsines, 0)
    phase_2 = np.where(np.logical_and(sines >= 0, cosines <  0), pi+arcsines,   0)
    phase_3 = np.where(np.logical_and(sines <  0, cosines <  0), pi+arcsines,   0)
    phase_4 = np.where(np.logical_and(sines <  0, cosines >= 0), -arcsines,     0)
    arcsines = phase_1 + phase_2 + phase_3 + phase_4

    if radian_range[0] <= radian_range[1]:
        return np.where(np.logical_and(arcsines >= radian_range[0], arcsines <= radian_range[1]),
                        output_ring, 0.0)
    else:
        return np.where(np.logical_or(arcsines >= radian_range[0], arcsines <= radian_range[1]),
                        output_ring, 0.0)
Radial arc with Gaussian fall-off after the solid ring-shaped
    region with the given thickness, with shape specified by the
    (start,end) radian_range.