No, sorry, right now you’ve got to manually pack and unpack everything from 1d arrays. It’s awkward.
We’re working on something right now to address this problem (https://github.com/stan-dev/math/pull/1641) but that won’t be finished until later this year (knock on wood).
Hi @bbbales2, thanks for your help again. So, I take it that it would also be impossible to assign an array of reals to a single element in x_r? Best way then would be to write a for loop that assigns individual elements from test_vector to x_r per iteration?