Suppose I have the following expression

```
system = x + y + z

```

And I would like to define a function that contains this function, without explicitly typing the right hand side of the above equation.

I tried:

```
systemfunction = Function[{x,y,z},system]

```

but this does not produce the desired result as the following evaluation yields:

```
systemfunction[1,1,1]

```

> 
> (x + y + z)[1,1,1]
> 
> 
>