where $\mathrm{x}$ is a vector with the unknown model parameters, and $\mathrm{A}$ is referred to as the *design matrix*. $\mathbb{E}(.)$ is the expectation operator. The random errors are given by $\epsilon$ and are assumed to have zero mean: $\mathbb{E}(\epsilon)=0$.
```
MMM
MMMMM
EXERCISE : show that the two expressions in the Definition above are indeed the same.
...
...
@@ -42,7 +42,7 @@ Parameter estimation requires specification of the underlying functional and sto