I am feeding in a data vector `b`

for sigma for the prior of `a`

. Will the statement below actually do what I want it to?

vector a ~ normal(0, vector b);

Stan tells me `a`

has no prior, but maybe that’s a bug. I want the i-th element in `a`

to have the i-th sigma in `b`

.

I think you should use `reals`

as the data type, (i.e., `real`

for 1d parameters and `real[]`

for n-dimensional parameters.

Off the top of my head, I’m not sure if that syntax works or not (I imagine that it would). If not, you can define a n-dimensional array of 0s e.g.,

```
transformed data {
real zeros[N] = to_array_1d( rep_vector(0, N) );
}
```

And then in the model block have something like `a ~ normal(zeros, b);`