mich_lung_xx            Gene expression data for Michigan lung cancer
                        study in Beer et al. (2002)
pumadyn_isample_x       Pumadyn dataset
s_soda                  S-SODA algorithm for general index model
                        variable selection
s_soda_model            S-SODA model estimation.
s_soda_pred             Predict the response y using S-SODA model.
s_soda_pred_grid        Predict the response y using S-SODA model in a
                        2-dimensional grid.
soda                    SODA algorithm for variable and interaction
                        selection
soda_trace_CV           Calculate a trace of cross-validation error
                        rate for SODA forward-backward procedure
