The convergence properties of the line transfer tests presented here are shown in Figs. 7-10. In each figure, we show the convergence rates, as measured by the relative corrections per iteration, for a number of test runs. In all tests show here we have used points and solid angle points for the 3D test case and 64 radial points for the 1D comparison test. The iterations were started with at all spatial points, this initial guess causes a relative error of about in at the outer zones for the case with and about in at the outer zones for the case with . The plots show that the iteration is useless even for the relatively benign case of . The operator splitting method delivers much larger corrections and is substantially accelerated by the Ng method, similar to the results shown in Paper I. The nearest-neighbor operator gives substantially better convergence rates than the diagonal operator, cf. Fig 7, for the test cases with with the convergence behavior of the diagonal operator is unstable, the corrections tend to show oscillations. The nearest-neighbor operator shows stable convergence with quickly declining corrections for all test cases, its convergence rate can be accelerated with Ng's method. The total number of iterations required for the nearest-neighbor operator is essentially identical to the 1D case with a tri-diagonal operator.
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