“…Formula (12) can be solved very efficiently by CG algorithm, and details of the strategy can be found in many literatures (TARANTOLA, 1987;MENKE, 1984;SACCHI and PORSANI, 1999;TRAD et al, 2002;JI, 2006). The weighting and the preconditioning matrices W d and W m at the i-th iteration of the CG algorithm are determined by using diagonal matrices: diag(W d ) i = |r i | -1/2 and diag(W m ) i = |m i | 1/2 , respectively, where m i is the Radon model at i-th iteration of the CG algorithm, r i is the standard deviation of residual r (HERRMANN et al, 2000;TRAD et al, 2002TRAD et al, , 2003JI, 2006).…”