The Stan Forums provide a community for asking and answering questions about all aspects of Stan. Before creating a new topic please search the Forums to see if your questions has already been answered, or check out the Stan FAQ.
When posting new topics we highly recommend that you simplify your problem as much as possible. It is much easier for the community to read and understand a small Stan program with clear names that highlights the given issue than a huge Stan program with obscure variable names and lots of irrelevant structure.
When creating a new topic please be careful to add the topic to the appropriate category. The Algorithms category is for questions pertaining to the computational algorithms in Stan, while Interfaces is for questions pertaining to installing and using the various Stan interfaces. Publicity is for sharing any work that uses or discusses Stan.
Modeling is the category dedicated to building and fitting models. Modeling: Specification is for when your Stan program doesn’t compile. Similarly, Modeling: Fitting Issues is for when your Stan program doesn’t recover reasonable values and Modeling: Performance is for when you want to optimize the speed of your fit. Finally, Modeling: Techniques is for general questions about Bayesian modeling building.
If you believe that you have found a bug, then please create an issue on the appropriate GitHub repository, such as the Stan Core Library or the Stan Math Library. Similarly, new feature requests should be made by creating new issues describing the request as detailed as possible.