STAN C++ RELEASE NOTES
======================================================================

v2.4.0 (20 July 2014)
======================================================================

New Features
------------
* L-BFGS optimization (now the default)
* completed higher-order autodiff (added all probability functions,
  matrix functions, and matrix operators);  tested up to 3rd order
* enhanced effective range of normal_cdf to prevent underflow/overflow
* added von Mises RNG
* added ability to use scalars in all element-wise operations
* allow matrix division for mixing scalars and matrices 
* vectorization of outcome variates in multivariate normal with efficiency boosts
* generalization of multivariate normal to allow rwo vectors as means
  and 

Reorganization
--------------
* move bin/print and bin/stanc to CmdStan;  no longer generating main
  when compiling model from Stan C++

New Developer
-------------
* Added Jeffrey Arnold as core Stan developer

Bug Fixes
---------
* modified error messages so that they're all 1-indexed instead of 0-indexed
* fixed double print out of times in commands
* const added to iterators to allow VS2008 compiles
* fix boundary conditions on ordered tests
* fix for pow as ^ syntax to catch illegal use of vectors (which
  aren't supported)
* allow zero-length inputs to multi_normal and multi_student_t
  with appropriate log prob (i.e., 0)
* fixed bug in inverse-Wishart RNG to match MCMCPack results
  with slightly asymmetric inputs
* fixed problem with compiling user-defined function twice
* fixed problem with int-only parameters for user-defined functions
* fixed NaN init problems for user-defined functions
* added check that user variable doesn't conflict with user function + doc
* disallow void argument types in user-defined functions

Code Cleanup and Efficiency Improvements
----------------------------------------
* removed main() from models generated from C++ Stan (they are
  now available only in CmdStan); removed no_main command options
* reserve vector sizes for saving for sample recorder
* removing many instances of std::cout from API (more still to go)
* removed non-functional Nesterov optimization option
* optimization code refactoring for testing ease
* better constant handling in von Mises distribution
* removed tabs from all source files
* massive re-org of testing to remove redundant files and allow
  traits-based specializations, plus fixed for 1-indexing

Testing
-------
* added tests for log_softmax, multiply_lower_tri_self_transpose, tcrossprod
* break out function signature tests into individual files, add many
  more
* enhanced cholesky factor tests for round trip transforms and
  derivatives
* extensive unit testing added for optimization 
* remove use of std::cout in all tests

Example Models
--------------
* lots of cleanup in links and models in ARM examples
* added BUGS litter example with more stable priors than in the 
  BUGS version (the original model doesn't fit well in BUGS as is, 
  either)

Documentation
-------------
* add infix operators to manual
* categorical_logit sampling statement	
* Cholesky factor with unit diagonal transform example
* example of using linear regression for prediction/forecasting with
  notes
* clarified some relations of naive Bayes to clustering
  vs. classification and relation to non-identifiability
* new advice on multivariate priors for quad_form_diag
* fix typo in multiply_lower_self_transpose (thanks to Alexey Stukalov)
* fix formatting of reserved names in manual
* fixed typo and clarified effective sample size doc
 

v2.3.0 (18 June 2014)
======================================================================

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
* 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)

New Developer
--------------
* added Marco Inacio as core developer

Optimizations
-------------
* turned off Eigen asserts
* efficiency improvements to posterior analysis print

Documentation
-------------
* 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 Aadler was particularly useful in pointing out and fixing
  documentation errors

Bug Fixes
------------
* 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)

Code Reorganizations & Updates
------------------------------
* 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)


v2.2.0 (14 February 2014)
======================================================================
Bug Fixes
-------------
* increment_log_prob is now vectorized and compiles with vector arguments
* multinomial random number generator used the wrong size for the return value
* fixed memory leaks in auto-diff implementation
* variables can start with the prefix 'inf'
* fixed parameter output order for arrays when using optimization

Features
-------------
* suppress command line output with refresh <= 0
* added 1 to treedepth to match usual definition of treedepth
* added distance, squared_distance, diag_pre_multiply, diag_pre_multiply to Stan modeling lnaguage
* added a 'fixed_param' sampler for use with the generated quantities block




v2.0.1 (24 October 2013)
======================================================================

Bug Fixes
----------------------------------
* fixed multi_normal distribution's gradient calculations
* fixed diagnose mode from the command line to work for matrices
* typos in the manual



v2.0.0 (16 October 2013)
======================================================================

This list is incomplete.  The 2.0.0 update is a huge fix, and this
list just represents what was clearly called out in pull requests.

Enhancements
----------------------------------
* all new hierarchical command-line interface
* compiler flags to build with Xcode 5 (which has too-small template-depth)
* BFGS optimization
* print variable name when initialization fails
* reserved function names (breaks backward compatibility)
* deprecate direct use of lp__ in favor of increment_log_prob()
* unfolded softmax for more efficiency, optimized and vectorized categorical
* new Cholesky factor data type
* upgraded to Boost 1.54 and Eigen 3.2.0
* added flag to suppress Jacobian adjustment in log prob (for
  optimizers)
* added Rayleigh distribution
* added Bessel (and modified Bessel) functions of first and second
  kind
* added Pochhammer functions (rising/falling factorials)
* completed vectorization of univariate distributions
* trapped use of "." in variable names and print error
* moved RStan into its own subproject
* rewrote writer interface for samples
* added delete method to chainables to allow exceptions in
  constructors
* added sort and rank functions
* improved doc and coding for GP example models
* shuffle function signature tests for test speed
* new gradient functionality for memory allocation and cleaning
  and to reduce code duplication

Bug Fixes
----------------------------------
* remove function signatures from undocumented functions
* fixed broken abs(real) signature;  deprecated abs(real) in favor
  of fabs(real)
* error checking for dirichlet
* fix bin/print to be row major
* suppress warnings for unused variables; cleanup truly unused ones
* fixed pow() boundary conditions with negative base, fractional
exponent
* fix model tests and error codes
* fix command-line return codes to be more compliant
* fix build parameter names to be more compliant with conventions
* fix integer vs. real problems in some RNGs
* fix print so that it prints expression values, not just names
* fix Newton optimization backtrack to eventually terminate with
  failure rather than looping infinitely
* fix CSV output from command for matrices (was transposed)
* fixes to allow Stan to build under Cygwin 
* fix double indexing on LHS of assignment
* fix nested expression prints to allow indexed array sizes in
  declarations
* fix parameterization of gamma RNG
* reserved model's class name as variable
* added vector size test in assignment
* fixed mixture examples
* fixed rep_vector to work with integer value
* fixed parser error message 
* fixed use of Boost NaN tests
* initialze local variables to NaN to prevent segfaults if used
  before defined
* remove unused includes from model header
* fix signed/unsigned warnings in tests and code
* validate that init=0 is valid starting value and raise error if not
* fix diag_pre_multiply loop bound


Doc
---------------------------------
* made all user-suggested cleanups and changes to doc
* new basic programming section
* new chapter for new command line



v1.3.0 (12 April 2013)
======================================================================

Enhancements
----------------------------------

Modeling Language
* forward sampling (random draws from distributions)
  in generated quantities
* added broadcast (repetition) functions for initializing
  matrices, vectors, and arrays
* better error messages in parser
* additional distributions: 
    + exp_mod_normal
    + gumbel 
    + skew_normal
* additional functions: 
    + mdivide_right_spd 
    + mdivide_left_spd
    + owenst
    + columns_dot_product
    + rows_dot_product
* broadcast (repetition) functions for vectors, arrays, matrices
    + rep_arrray
    + rep_matrix
    + rep_row_vector
    + rep_vector    

Command-Line
* added option to display autocorrelations in the command-line program
  to print output
* changed default point estimation routine from the command line to
  use Nesterov's accelerated gradient method, added option for point
  estimation with Newton's method

RStan
* added method as.mcmc.list()
* compatibility with R 3.0.0

C++/Internal
* refactored math/agrad libs in C++ to separate files/includes,
  remove redundant code, more unit tests for existing code
* added chainable_alloc class for caching solver results
* generalized VectorView with seq_view
* templated out generated code for efficient double-only operation
  on model log probs w/o gradients

Doc
* additions to user's guide w. sample models
    + stochastic volatility example with source, optimized source, 
      simulation
    + time series, moving average, standardization for linear 
      regression, hidden Markov models, with examples
* manual's index is now hyperlinked
* added additional acknowledgements to manual
* added full description of differences between sampling
  statement and lp__
* fixed general normal mixture model example

Testing
* split unit tests from distribution tests

Bug Fixes
----------------------------------
* fixed derivative in multi_normal_prec distribution function
* double-based log_prob functions return the same value as var-based
  log_prob_grad functions
* calls to lgamma are now using boost's lgamma function
* patched transform to work with Eigen 3.2 beta
* all probability distribution functions and cumulative distribution
  functions behave properly with 0 length vector arguments
* fixed error in definition of hypergeometric pmf
* fixed arguments to nesterov optimization ctor in command 
* fixed issue with initialization matrices being read improperly 
* Use fabs() instead of abs() in unit_vector_constrain. 
* typos in the manual
* rstan: 
  + fixed crash in R when index is out of bounds using set_cppo("fast")
  + io_context fix skipping len=0
  + fix the typo in manual (dims -> dim)
  + add require(inline) to fix the problem with loading sysdata.rda


v1.2.0 (6 March 2013)
======================================================================

Enhancements
----------------------------------
* full mass matrix estimation during warmup
* expose model log_prob and gradient functions in RStan for use
  in other packages (such as optimizers)
* command-line program to display output from multiple chains
  with parameter-by-parameter mean, se, sd, quantiles, and R-hat
* probability function speed improvements with vectorization
* created Stan contributed repositories for user-contributed
  and experimental features (first entry is an emacs mode)
* modified makefiles so targets are the same under Windows,
  Linux, and Mac

New Functions
----------------------------------
* most of the cumulative distribution functions (see the documentation
  index for the full list of supported functions)
* added monitor() function in RStan

Bug Fixes
----------------------------------
* disabled Boost asserts in parser to quiet R's warnings
* enabled prints in generated quantities block
* various documentation patches
* fixed memory leak in matrix operations leading to leaks in 
  multivariate probability function use
* wrapped call to gradient log prob to catch unexpected exceptions
* fixed matrix resize issue on Windows that caused models to fail
  at optimization levels above 0
* fixed bug in print preventing hyphens or grave accents from 
  priting
* fixed issue preventing matrix rows from being assigned on the
  left side of an assignment statement
* clearer error messages on matrix and other function arguments


v1.1.1 (5 February 2013)
======================================================================

Bug Fixes
----------------------------------
* fixed bug in comparison operators, which swapped operator< with
  operator<= and swapped operator> with operator>= semantics
* auto-initialize all variables to prevent segfaults
* atan2 gradient propagation fixed
* fixed off-by-one in NUTS treedepth bound so NUTS goes
  at most to specified tree depth rather than specified depth + 1
* various compiler compatibility and minor consistency issues
* fixed bug in metaprogram preventing lower/upper bound constraints 
  on matrices
* fixed print error for number of kept samples
* fixed floating point literal precision issue in code generation
* fixed bug in bernoulli_log for boundary chance of success 
  theta=0 or theta=1
* many doc patches (mostly due to user comments -- thanks!)
* replace boost sign() to avoid compiler conflicts
* trapping mismatched dimension assignments in arrays, 
  matrices, and vectors

Enhancements
----------------------------------
* user's guide chapters w. sample models
    + gaussian processes
    + measurement error and meta-analysis
    + clustering (soft k-means, LDA, naive Bayes)
    + ARCH, GARCH model section in regression chapter
* sample models
    + hidden Markov models (HMMs)
    + non-negative matrix factorization (NNMF)
* speed improvements to multivariate models and matrix solvers
    + mdivide_left, mdivide_left_tri_low, mdivide_right,
      mdivide_right_tri_low
    + determinant, log determinant
    + inverse
* much more extensive probability tests
* unstacked vari for multivariate auto-diff unfolding
* faster multiply self transpose / columns_dot_self
* cleaned up error messages for size mismatches in accessors
* simplified vector view expression template parameterization
* cleaned up many --pedantic compiler warnings

New Functions
----------------------------------
* log absolute determinant, with optimized gradients
* probability functions
    + multivariate normal, precision parameterization
* model timing and n_eff output in CSV for all test models
* ongoing vectorizations and reparameterizations 
  of probability functions
* faster Phi_approx computing an approximate cumulative unit
  normal density
* added dims() function to extract dimensions of arrays of scalars,
  vectors, and matrices  
* added size()  function to extract the number of elements in an array


v1.1.0  (17 Dec 2012)
======================================================================
-- Backward Compatibility Issue
   * Categorical distribution recoded to match documentation;  it
     now has support {1,...,K} rather than {0,...,K-1}.  
   * (RStan) change default value of permuted flag from FALSE to TRUE for
     Stan fit S4 extract() method
-- New Features
   * Conditional (if-then-else) statements
   * While statements
-- New Functions
   * generalized multiply_lower_tri_self_transpose() to non-square
     matrices
   * special functions: log_inv_logit(), log1m_inv_logit()
   * matrix special functions: cumulative_sum()
   * probability functions: poisson_log_log() for log-rate 
     parameterized Poisson
   * matrix functions: block(), diag_pre_multiply(), diag_post_multiply()
   * comparison operators (<, >, <=, >=, ==, !=)
   * boolean operators (!, ||, &&)
   * allow +/- inf values in variable declaration constraints
-- RStan Improvements
   * get_posterior_mean() method for Stan fit objects
   * replaced RcppEigen dependency with include of Eigen source
   * added read_stan_csv() to create Stan fit object from CSV files of
     the form written to disk by the command-line version of Stan
   * as.data.frame() S3 method for Stan fit objects
-- Bug Fixes
   * fixed bug in NUTS diagonal resulting in too small step sizes
   * fixed bug introduced in 1.0.3 that hid line and column number
     bug reporting
   * added checks that data dimensions match as well as sizes
   * removed non-symmetric versions of eigenvalues() and eigenvectors()
   * testing identifiers are not reserved words in C++/Stan
   * trapping/reporting locations of errors in data and init reads
   * improvements in dump data format reader for more R compatibility
     and more generality
   * fix bug in bernoulli logit distro tail density
-- Code Improvements
   * templated out matrix libs to reduce code duplication
   * vectorized auto-dif for tcrossprod() and crossprod()
   * optimizations in Wishart
   * vectorization with efficiency improvements in probability distributions
-- Libraries Updated
   * Eigen version 3.1.1 replaced with version 3.1.2
   * Boost version 1.51.0 replaced with version 1.52.0
-- Manual Improvements
   * New chapter on univariate and multivariate variable transforms
   * Many consistency improvements and typo corrections
   * Information on running command line in parallel from shell



v 1.0.3 Release Notes (25 Oct 2012)
======================================================================
Stan Bug Fixes:
 -- error output in stanc now directed to standard error
 -- catching all exceptions thrown in stanc to prevent core dumps
 -- parser now accepts variable names starting with "int" and "real"
    in first assignment after declaration
 -- now catching unknown truncation cdfs and vectorizations in stanc
 -- (hopefully) less scary message for domain error rejects
 -- removed use of assert(); replaced with exceptions where
    appropriate
 -- fixed boundary condition on reporting max init retry failures
 -- fixed initialization errors in tests that failed on some platforms
 -- improved error checking for matrix size args to prevent segfaults
 -- fixed boundary condition on bounded transform to allow
    beta(0.8,0.8) samples near 0 or 1
Stan New Features:
 -- mdivide_left_tri_low, mdivide_right_tri_low functions
 -- all univariate continuous densities vectorized
 -- better error checking for transforms 
 -- new error return type in stanc for invalid arguments
 -- lower and upper bounds for vectors, row vectors, and matrices
 -- command parameter refresh <= 0 turns off iteration reporting
 -- int divisions produce warnings in stanc
 -- errors caused by invalid transformed parameters include var name
 -- various efficiency improvements and error handling for boundary
    conditions and special cases of probability functions
 -- simplified matrix code with heavier use of templating
Stan Manual Additions:
 -- example of defining new distribution with parameters
 -- diff report vs. previous versions
 -- updated for range constraints on vector, row vector, matrix
 -- updated Eigen licensing information (now MPL, was LGPL)
 -- fixed alpha ordering issue in function index due to bolding
RStan Bug Fixes:
 -- bug of setting parameter epsilon_pm wrongly for NUTS 
 -- fixed seed reset so results match Stan
RStan New Features:
 -- return empty stanfit object upon error such as incorrect data
    input, wrong argument specification, etc. Previously, it will
    stop. The empty stanfit includes the compiled model, so it can be
    reused.
 -- add function stan_demo() to run examples included in Stan. 
 -- add function sflist2stanfit() to merge a list of stanfit objects 
    into one, to facilitate user-level parallelism. 
 -- add S3 method as.matrix, as.array, is.array, dim, 
    dimnames for stanfit objects. 
 -- specify seed using string of digits in addition to numbers  
 -- turn off refresh if value <= 0


V 1.0.2 Release Notes (28 Sep 2012)
----------------------------------------------------------------------
Bug Fixes:
  -- check ranges for LHS of assignment to prevent seg faults
  -- added matrix size and shape tests to avoid seg faults
  -- changed matrix to throw domain_error rather than illegal_argument
  -- removed template variable names from distribution error msgs
  -- indexing fixed for arrays of matrix/vector/row_vector
  -- fixed sd() and variance() to return 0.0 for sequences of size 1
  -- fixed void return type in auto_covariance
  -- patch truncation to return -inf for variates out of range
  -- upgraded BUGS ring model to use constraints plus tan2()
New Features:
  -- print statements
  -- multiply_lower_tri_self_transpose function
  -- vectorized several probability functions (see the manual)
Manual Additions:
  -- programming guide: IRT models 
  -- new appendix: style guide
  -- new appendix: migrating from Stan
  -- new index: function and distribution index


v1.0.1
----------------------------------------------------------------------
Patch release.


v1.0.0
----------------------------------------------------------------------
First release.






Sync between RStan and Stan Command-line
========================================

Top-Level Command
Cmd:    stan/gm/command.hpp
RStan:  rstan/rstan/inst/include/rstan/stan_fit.hpp
        rstan/rstan/inst/include/rstan/stan_args.hpp
        rstan/rstan/R/rstan.R

libstan.a
Cmd:    any XXX.cpp file added to makefile
RStan:  rstan/rstan/src/YYY__XXX.cpp


stanc translator
Cmd:    stan/command/stanc.cpp
R:      rstan/rstan/src/stanc.cpp


output analysis
Cmd:    stan/mcmc/chains.hpp
R:      rstan/rstan/src/chains.cpp

var_context impl
Cmd: 
R: rstan/rstan/inst/include/rstan/io/rlist_ref_var_context.hpp 

makefiles
Cmd:    add .cpp files, makefile,  make/make*
R:      rstan/rstan/src/Makefile{,.win}


boost/eigen version 
Cmd:    lib/boost_x.xx.x/, lib/eigen_x.x.x, etc.
R:      rstan/rstan/src/Makefile{,.win} 
        rstan/rstan/R/options.R

author list 
Cmd:   web/mc-stan.org/development-team.html
R:     rstan/rstan/DESCRIPTION
       rstan/rstan/man/rstan.Rd