auto: one of the three methods below is automatically computed
gauss: direct method, recommended for computing small/medium models
gradient: solving iterative method which is memory saving but not CPU time saving, recommended for computing huge models
gauss R6: fast Gauss method recommended for computing large size models
online 给的解释
我虽然可以大概区分下可是究竟他们的 理论区别是什么呢?