QBIC                    High dimensional BIC for quantile regression
                        model
QICD                    Fit a nonconvex penalized quantile regression
                        model
QICD-package            Estimation of coefficients of nonconvex
                        penalized quantile regression model
QICD.BIC                BIC for QICD on tuning parameter searching
QICD.cv                 Cross-validation for QICD
allzero                 Judge an all zero vector
checkloss               Obtain the checkloss for quantile regression
