Hi,

Let’s suppose that I have a matrix like the following

`let matrix = DMatrix::<f64>::zeros(10, 10);`

I would like to update some part of the matrix in a very similar way of Eigen blocks. For instance, the upper right corner of the matrix.How can I do that in **nalgebra**?

Also, I know that there are the `set_column`

and `set_row`

methods, but I am wondering if I can make a mutable slice of a matrix and replace it with something else. I have tried the following code but it does not work and I still don’t understand why

```
let mut matrix = DMatrix::<f64>::zeros(10, 10);
let mut slice = matrix.index_mut((.., ..2));
let arr = DMatrix::<f64>::zeros(10, 2);
slice = arr;
```

Thanks for your help!