Release v2.3.0 · stan-dev/stan

We had a record number of user-submitted patches this go around.
Thanks to everyone!

New Features

user-defined function definitions added to Stan language
cholesky_corr data type for Cholesky factors of correlation matrices
a^b syntax for pow(a,b) (thanks to Mitzi Morris)
reshaping functions: to_matrix(), to_vector(), to_row_vector(),
to_array_1d(), to_array_2d()
matrix operations: quad_form_sym() (x' *Sigma * x), QR decompositions
qr_Q(), qr_R()
densities: Gaussian processes multi_gp_log(), multi_gp(),
and alternative negative binomial parameterization neg_binomial_2()
random number generator: multi_normal_cholesky_rng()
sorting: sort_indices_*() for returning indexes in sorted order by
value
added JSON parser to C++ (not exposed through interfaces yet; thanks
to Mitzi Morris)
many fixes to I/O for data and inits to check consistency and
report errors
removed some uses of std::cout where they don't belong
updated parser for C++11 compatibility (thanks to Rob Goedman)

Clarified licensing policy for individual code contributions
Huge numbers of fixes to the documentation, including many
user-contributed patches (thanks!), fixes to parallelization in
CmdStan, Windows install instructions, boundaries for Dirichlet and
Beta, removed suggestion to use floor and ceiling as indices,
vectorized many models, clarified that && doesn't short circuit,
clarified von Mises normalization, updated censoring doc (thanks
to Alexey Stukalov), negative binomial doc enhanced, new references,
new discussion of hierarchical models referencing Betancourt and
Girolami paper,
Avraham Adler was particularly useful in pointing out and fixing
documentation errors

fixed bug in lkj density
fixed bug in Jacobian for corr_matrix data type
fix cholesky_cov_matrix test code to allow use as parameter
fixed poisson_rng, neg_binomial_rng
allow binary operations (e.g., < and >) within range constraints
support MS Visual Studio 2008
fixed memory leaks in categorical sampling statement, categorical_log
function, and softmax functions
removed many compiler warnings
numerous bug fixes to arithmetic test code conditions and messages,
including calls from
fixed model crashes when no parameter specified
fixed template name conflicts for some compiler bugs (thanks Kevin
S. Van Horn)

CmdStan is now in its own repository on GitHub: stan-dev/cmdstan
consolidate and simplify error handling across modules
pulled functionality from CmdStan command class and PyStan and RStan
into Stan C++
generalized some interfaces to allow std::vector as well as Eigen
for compatibility
generalize some I/O CSV writer capabilities
optimization output text cleaned up
integer overflow during I/O now raises informative error messages
const correctness for chains (thanks Kevin S. Van Horn)