论文中急用，正在用林光平的书学习gauss。但是感觉上手比较慢。这样下去论文不知道什么时候能写出来。

: 急用, It is not easy, you must have a correct time span expectation for this if you are really going to make sth true/correct.

Frequently, there will be numerical problems. such the covariance matrix become non-positive definite during the optimization. furthermore, some program may requires 20 hours of cpu time depending on the problem and the Computer.