Is it possible to completely fix the `stepsize__`

parameter? Equivalently I tried to run the HMC sampler with `warmup=0`

but I got flat lines and zero-likelihood/negative poisson parameter warnings even when setting the initial parameters to the “true” values. Is that not allowed in Stan?

I was under the impression that with NUTS it may be necessary to have some optimization during the burn-in period, but for HMC only the step size required optimization, so it did not need anything else if a step size (as well as `int_time`

was provided).

Additionally, since I’m asking about sampler options, is there one to suppress all warnings during sampling? `verbose=False`

doesn’t seem to eliminate all messages, and for long runs I would like to see only the percent progress.

Thanks.