To accurately invert for velocity in a model with a blocky
interval velocity inversion using Dix
inversion, we set up our optimization objective function using

criterion. In this study, we analyze and test an improved version of
the Iterative Reweighted Least Squares (IRLS) solver, a hybrid

solver and a conjugate direction

solver. We use a 1-D
synthetic velocity data set and a 1-D field RMS velocity data
set as test cases. The results of the inversion are promising for
applications on realistic geophysical problems.