Smoothing and Regularization with Modified Sparse Approximate Inverses

Figure 5

Reconstruction error against the iteration for the 1D blur operator 𝐵₂ and the original data 𝑥₁ of size 𝑛=10³ affected by random noise of order 0.1% (a) and 1% (b), respectively. CG is compared to CG using the normal equations, PCG for 𝐵₂ and 𝐵^𝑇2𝐵₂ using MSPAI with 𝑅3_𝐺1.

(a) Noise level 0.1%

(b) Noise level 1%