Brian Ward

I think there are alternative ways of avoiding the issue only cropping up in stanc3. The simplest I can think of is just having the expression tests (which only take...

> The full test suite takes like 12 hours to run so honestly an extra 2 hours is actually kind of fine imo Yeah, I just wish if we were...

> a "quick mode" that is the default when a PR is opened that reads the diff, looks at the name of the files changed, then greps and only runs...

> The loss of two hours of wait time to prevent upstream failures is worth it I just wanted to make sure it was clear: these upstream failures are in...

It would be possible, but I don't think that is an easy change in the current test infrastructure, since `make` doesn't tell you when _some_ targets are done. I'd be...

I think something of that flavor could work as long as anything shared between tests (like TBB or Sundials) was already built, otherwise you'd get filesystem races. Worth exploring things...

The hessian could be represented as a strided matrix (essentially a rowise or columnwise flattening). Since it should always be symmetric it doesn’t even matter which direction you flatten in

Do any of the implicit functions support fvars? I was under the impression that none of them did, and that this was semi-intentional

Here's a list of functions exposed in the Stan language which would be candidates to use with `stan/math/fwd/functor/finite_diff.hpp`: - [x] `integrate_1d` (https://github.com/stan-dev/math/pull/2929) - [ ] `map_rect` - [ ] `reduce_sum`...

Not to be a member of the peanut gallery, but wouldn't that mean this package basically has to maintain both something at the level of complexity of rstan _and_ an...