Hello!

Suppose I have an array of vectors, eg

```
data{
int T;
int n;
}
parameters{
row_vector[n] v[T];
}
```

and suppose I want to copy this into a matrix so I can use vectorised sampling statements. Which of these is more efficient?

Option 1:

```
model{
matrix[T,n] A;
for(i in 1:T){
for(j in 1:n){
A[i,j] = v[i,j];
}
}
to_vector(A) ~ normal(....);
}
```

Or option 2?

```
model{
matrix[T,n] A;
for(i in 1:T){
A[i] = v[i];
}
}
to_vector(A) ~ normal(....);
```

Thanks!