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. Author manuscript; available in PMC: 2018 Jan 1.
Published in final edited form as: IEEE Trans Med Imaging. 2016 Aug 31;36(1):236–250. doi: 10.1109/TMI.2016.2604568

TABLE II.

Computational costs per iteration.

method computational cost
Gradient-based
(classic adjoint)
𝒪(N7/3) + 2𝒪(N5/3)
Gradient-based
(generalized adjoint)
2𝒪(N7/3) + 2𝒪(N5/3)
Gradient-based
(straightforward)
𝒪(N7/3) + (M + 1)𝒪(N5/3)
Gauss-Newton 𝒪(N3) + 𝒪(N7/3) + (M + 1)𝒪(N5/3)