Suppose I generate the following two files using `JLD`

```
X1=randn(5,10^4);
X2 = [randn(5) for i=1:10^4];
@save "X1.jld" X1;
@save "X2.jld" X2;
```

Both data structures have the same amount of information, but `X1.jld`

takes up 404 KB, while `X2.jld`

takes up 3.6 MB. Is there a way to get data formatted `X2`

to behave more efficiently or do I just need to rewrite my code?