SS: long infusion time #6
Description
Summary:
Torsten does not properly handle the case when the infusion time is longer than the inter-dose interval for steady states.
Description:
Neither the analytical nor the matrix exponential solution address the case where the infusion time (delta = amt / rate) is longer than the inter-dose interval (ii). The general and the mix solver do not handle the SS case, though I'm almost with an implementation for the former.
I'll post a solution for the long infusion time, but it involves a discrete latent parameter which would cause HMC some grievance.
For the next release, I'll focus on getting the SS solution for short infusion times. The code will throw an exception when delta > ii, and point the user to a section in the manual.
Reproducible Steps:
The solution does not compare to what I obtained with mrgsolve, see directory math/torsten/GeneralSS under the unit tests, on the issue-29-general-SS branch.
Current Output:
I tried this with PKModelOneCpt and get the wrong result (see above). If I only run Pred1_one I get an assert error -- not sure why the latter happens in one case and not the other.
Expected Output:
For the next release: an informative exception when delta > ii
For future releases: a proper solution when delta > ii
Current Version:
torsten v0.83
stan v2.15.0