可以看到

变步长未必会需要更长的时间

因为它是一种自适应的方式

如果某阶段情况理想的话

就会用最大步长来做

那就会很快

-can see variable step may not need a longer period of time because it is an adaptive way if a certain phase of the the ideal would be the greatest step will be to do it quickly