Now, we all know by now that I'm not a programmer (that makes me very sad sometimes and may frustrate some of you at times), but I know a good paper and presentation when I see one. Christopher Bost knows how to teach a topic. I went to his Tuesday
To a statistician, the LAG function (which was introduced in SAS/IML 9.22) is useful for time series analysis. To a numerical analyst and a statistical programmer, the function provides a convenient way to compute quantitites that involve adjacent values in any vector. The LAG function is essentially a "shift operator."
Getting the axis values just right generally requires some work, and the values you want can change from case to case. One such example was discussed by Dan Heath in his post on custom axis values. Here Dan shows the usage of non uniform axis values using the VALUES option on
