I’m trying to use `ModelingToolkit.build_function`

to generate a C function with “vector-like” inputs, and “matrix-like” outputs. I would prefer **not** to have the left-hand-side of the equations in the state vector, but I can’t figure out how to build a `CTarget`

function without including the left-hand-side in the “variables” argument.

**My Attempt**

```
import Pkg
Pkg.activate(tempdir())
Pkg.add("ModelingToolkit")
using ModelingToolkit
@variables x[1:2,1:2] y[1:4]
eqs = x[:] .~ y
build_function(eqs, [y..., x...];
target=ModelingToolkit.CTarget())
```

**Output**

```
"void diffeqf(double* du, double* RHS1) {\n du[4] = RHS1[0];\n du[5] = RHS1[2];\n du[6] = RHS1[1];\n du[7] = RHS1[3];\n}\n"
```

The output above has `du`

first indexed at `4`

, because it is the *4th through 8th* element in the state vector. I’d prefer for `du`

and `RHS1`

to be entirely separate. **How can I best accomplish this?**