I have a model with decision variables like this

```
model = Model(Cbc.Optimizer)
@variable(model, x[1:num_groups, 1:size(data, 1)], Bin)
```

and I need to be able to use the values of `x`

to return a submatrix from another matrix `dm`

. I’ve tried like this

```
@objective(model, Min, sum(sum(dm[BitArray(x[i,:]), BitArray(x[i,:])]) for i in 1:3))
```

but I get:

```
julia> @objective(model, Min, sum(sum(dm[BitArray(x[i,:]), BitArray(x[i,:])]) for i in 1:3))
ERROR: MethodError: Cannot `convert` an object of type VariableRef to an object of type Bool
```

I thought I had tricked it into working with this monstrosity because it didn’t throw an error but the objective value always turns out to be 0.0 this way:

```
sum([sum(dm[[i for i in 1:size(data,1) if value.(x)[j,:][i] == 1.0], [i for i in 1:size(data,1) if value.(x)[j,:][i] == 1.0]]) for j in 1:num_groups])
```

Is there a way to convert the values of `x`

so that I can use them in the same way one would use a `BitArray`

?