![Store vectors of different lengths in a matrix](https://blogs.sas.com/content/iml/files/2017/01/ProgrammingTips-2.png)
In the SAS/IML language, you can only concatenate vectors that have conforming dimensions. For example, to horizontally concatenate two vectors X and Y, the symbols X and Y must have the same number of rows. If not, the statement Z = X || Y will produce an error: ERROR: Matrices