• Step 1. Choose the set of M points in the real space ({r k } M k=1 ). The maximal value max{r k } should not exceed the value r max = π/∆s, where ∆s is the mean increment for the data in s-space (see Sec. III). The initial regularization parameter α ≥ 0 should also be chosen. Switching to regularized approach (α > 0) is recommended if the chosen increment ∆r is smaller than the value ∆r min = 2π/ max {s i } N i=1 , or even stricter, 69 ∆r min = 2π/ max {s i } N i=1min {s i } N i=1 .