Fix the function corresponding to the

`intercept`

argument. The intercept argument controls whether to include the intercept, but since the SPSP algorithm estimates the intercept separately. It needs to be dealt with separately.The

`standardize`

only control the standardization of covariates.

Implement the Selection by Partitioning the Solution Paths procedure in the SPSP() and SPSP_step() functions;

Add fitfun.SP functions to obtain the solution paths for the SPSP algorithm;

Include one high-dimensional data for illustration purpose.