Enable multi_gp in the language.
Add multi_gp to the manual.
Fix inverse in manual.
Fix function signature.
Add agrad unit tests for multi_gp_log.
adding test for run_markov_chain that traps the current output for CmdStan
adding const to run_markov_chain arguments
adding additional arguments to run_markov_chain with defaults.
adding additional arguments to run_markov_chain with defaults.
updating test to push in prefix, suffix, and the ostream
removed std::cout in print_progress; called the fully specified print_progress in run_markov_chain, removed defaults out of run_markov_chain
removed std::cout in print_progress; called the fully specified print_progress in run_markov_chain, removed defaults out of run_markov_chain
adding comment to test
adding prefix, suffix, and osream arguments to stan::common::sample and warmup; added tests
adding a StartTransitionCallback (useful for RStan) to run_markov_chain, sample, warmup, and the calls from command()
Added to_matrix, to_row_vector, to_array and flatten. Extended to_vector
Changes and improvements to to_matrix, to_row_vector, to_array_1d, to_array_2d, to_vector. flatten renamed to array_1d.
Merge branch 'develop' of https://github.com/stan-dev/stan into develop
adding documentation to mcmc_writer
added an as_csv class