_N_e_w_s _f_o_r _p_a_c_k_a_g_e '_p_o_m_p'

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _2._3:

        • The C API for ‘pomp’ is no longer explained only in comments
          in the “pomp.h” header file.  It is now described and
          explained in the new C API vignette.

        • The new ‘pomp_cdir’ global option allows one to set the
          directory holding C snippet files globally.

        • A bug caused by re-use of the ‘cfile’ argument has been
          fixed.  Re-use now triggers an error, with an informative
          message.

        • Some documentation improvements.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _2._2:

        • A bug in ‘runifDesign’ (and therefore ‘profileDesign’ when
          ‘type="runif"’) has been fixed.

        • There are now ‘plot’ methods for objects of classes
          ‘probe_match_objfun’ and ‘spect_match_objfun’.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _2._1:

        • The ‘melt’ function can now be applied to arbitrary ‘pomp’
          objects.

        • A new function, ‘runifDesign’ allows construction of design
          matrices using samples from multivariate uniform
          distributions.

        • The ‘profileDesign’ function takes a new argument, ‘type’,
          with two options: ‘"sobol"’, the default, constructs the
          design using ‘sobolDesign’, as before.  ‘"runif"’ uses the
          new ‘runifDesign’ function.

        • A new example, comprising models and data for the 2014--2016
          west African Ebola virus disease outbreak, is included.  See
          ‘?ebola’ for details.

        • It is now possible to adjust the observation times and
          zero-time in the ‘sir’ and ‘sir2’ examples.  One can also
          change the default RNG seed used in generating the simulated
          data.

        • The codes underlying the ‘rprocess’ workhorse have been
          streamlined to obviate an unnecessary copy operation.  As a
          result, the interface to the ‘rprocess’ workhorse has been
          changed.

        • The interface to the new ‘flow’ workhorse has been changed to
          match.

        • The new ‘flow’ workhorse allows integration/iteration of the
          deterministic skeleton at arbitrary times from an arbitrary
          initial condition.

        • When ‘coef’ is applied to a ‘listie’, the result can be more
          usefully ‘melt’ed.

        • The probe-names returned by ‘probe.acf’ and ‘probe.ccf’ have
          changed.

        • A bug, whereby the ‘coef’ method from other packages was
          masked, has been fixed.

        • Errors in the documentation have been corrected.

        • There is a new ‘as.data.frame’ method for ‘listie’s.

        • Some problems with the exposure of internal objects for
          package developers have been corrected.

        • The ‘magrittr’ pipe operator, ‘%>%’, is now re-exported.

        • More examples have been included.

        • Minor changes to error messages.

        • The names of the ‘objfun’ methods have been changed to
          ‘probe_objfun’, ‘spect_objfun’, ‘traj_objfun’, and
          ‘nlf_objfun’.

        • The package directory structure has been modified to include
          a new ‘examples’ directory, which holds the examples used in
          the documentation.

        • The names of the ‘objfun’ methods have been shortened.

        • It is now permissible that the sequence of observation times
          (and sequences of covariate times) be merely non-decreasing
          sequences.  Previously, ‘pomp’ insisted on strictly
          increasing time sequences.

        • The default cooling schedule (‘cooling.type’) in ‘mif2’ is
          now “geometric”, in contrast to “hyperbolic”, as before.

        • ‘pomp’ now requires at least R version 3.5.

        • The ‘zeronames’ argument has been renamed ‘accumvars’.

        • In the course of ordinary work, one should never need to
          interact with the low-level ‘pomp’ constructor function now.

        • The ‘pompExample’ function has been dropped.  The various
          examples are now included as regular functions that construct
          ‘pomp’ objects.

        • The ‘bbs’ example has been dropped.

        • One can now modify basic model components at (almost) any
          stage in a pipeline of ‘pomp’ computations.  All the
          top-level inference functions, plus ‘probe’, ‘pfilter’, and
          ‘simulate’ now allow modification of basic model components.

        • The ‘rprocess’ plugins ‘onestep.sim’, ‘discrete.time.sim’,
          ‘euler.sim’, ‘gillespie.sim’, and ‘gillespie.hl.sim’ have
          been renamed ‘onestep’, ‘discrete_time’, ‘euler’,
          ‘gillespie’, and ‘gillespie_hl’, respectively.  The old usage
          is available but deprecated.

        • One can now call ‘simulate’ on a model without reference to
          any data.

        • The covariate table facility (‘covariate_table’) now supports
          piecewise constant interpolation.

        • The syntax with which one includes covariates via
          ‘covariate_table’ has become more flexible.  Specifically,
          the arguments to ‘covariate_table’ are now evaluated
          sequentially, so that later ones can depend on earlier ones.
          Once evaluated, the covariates are bound column-wise into a
          single data frame.

        • The manner in which one writes R functions to specify basic
          model components has been totally changed.  Before, one wrote
          functions that took specific arguments such as 'x', 'params',
          and 'covars'.  Now, one writes such functions with any or all
          state variables, observables, covariates, and/or time as
          arguments.

        • ‘simulate’ now returns more informative results when
          simulations from multiple parameter sets are simultaneously
          computed.  Specifically, if ‘params’ has column names, these
          are used to identify the resulting simulations.  Thus when
          ‘format = "pomps"’ (the default), the names of the resulting
          list will be constructed from the column names of ‘params’.
          Likewise, when ‘format = "arrays"’, the resulting arrays will
          have informative column names; When ‘format = "data.frame"’,
          the identifier variable will make use of the column names.

        • The basic particle filter, ‘pfilter’, has a simpler mode of
          operation: ‘params’ should be a single parameter set only.
          That is, it is no longer possible to pass a matrix of
          parameters to ‘pfilter’.

        • The Liu-West algorithm, ‘bsmc2’, has a simpler mode of
          operation: ‘params’ should be a single parameter set only:
          the SMC particles are drawn from ‘rprior’.

        • The ‘as.data.frame’, ‘states’, and ‘obs’ options for
          ‘simulate’ have been done away with.  One now chooses the
          format of the returned simulations via the ‘format’ argument.
          When one simulates at multiple parameter sets, list names,
          array ‘dimnames’, or identifying variables in the output data
          frame help to correlate simulations with parameter sets.

        • The ‘as.data.frame’ argument to ‘trajectory’ has been removed
          in favor of a new ‘format’ argument that allows one to choose
          between receiving the results in the form of an ‘"array"’ or
          a ‘"data.frame"’.

        • All the basic model components now have defaults.

            • The default ‘rinit’ behavior remains as it was: it
              assumes the initial state distribution is concentrated at
              a point mass determined by parameters with “‘.0’” or
              “‘_0’” suffices.

            • The default process model is “missing”: calls to
              ‘dprocess’ and ‘rprocess’ will result in missing values
              (‘NA’).

            • The default measurement model is “missing” as well.

            • The default prior is flat and improper: all calls to the
              default ‘dprior’ result in ‘1’ (‘0’ if ‘log = TRUE’, and
              all calls to ‘rprior’ result in ‘NA’.

            • The default skeleton is missing.

            • The default parameter transformations remain the
              identity.

        • The ‘transform’ argument present in many ‘pomp’ algorithms
          has been removed.  Parameter transformations are now
          automatically performed when appropriate.  The default
          parameter transformation remains the identity.

        • The old ‘probe.match’ and ‘traj.match’ functions have been
          removed.  The new approach to parameter estimation based on
          numerical optimization involves constructing stateful
          objective functions.  There are now three of these:
          ‘traj.match.objfun’, ‘probe.match.objfun’, and
          ‘spect.match.objfun’.

        • The documentation system has been thoroughly overhauled.

        • In ‘skeleton’, the ‘t’ argument has been replaced by ‘times’,
          to make this uniform with the other workhorse functions.

        • Covariates are now included using the ‘covariate_table’
          construction, passed via the ‘covar’ argument to ‘pomp’.  The
          ‘tcovar’ argument is no longer used.

        • Instead of providing separate ‘fromEstimationScale’ and
          ‘toEstimationScale’ arguments to ‘pomp’, one now provides a
          single ‘partrans’ argument constructed by means of the new
          function ‘parameter_trans’.  In addition, references to
          “fromEstimationScale” and “toEstimationScale” have been
          abbreviated to “fromEst” and “toEst”, respectively,
          throughout the package.

        • When writing C snippets for parameter transformations, the
          notation ‘T_p’ refers to the value of ‘p’ on the estimation
          scale.  Thus, if parameter alpha is to be log-transformed for
          estimation, the ‘toEst’ snippet would contain the line
          ‘T_alpha = log(alpha);’ and the ‘fromEst’ snippet would
          include ‘alpha = exp(T_alpha);’.

        • The ‘parameter_trans’ function now takes optional arguments
          ‘log’, ‘logit’, and ‘barycentric’, with names of parameters
          to be log-, logit-, and log-barycentric transformed,
          respectively.

        • The ‘measurement.model’ argument to ‘pomp’ has been removed.
          It is now necessary to specify the measurement model directly
          using ‘rmeasure’ and/or ‘dmeasure’.

        • The ‘initializer’ is no longer referred to by that name.  It
          is now ‘rinit’, since it draws from the distribution of the
          latent state at the initial time.  The low-level function
          ‘init.state’ has been replaced by ‘rinit’.

        • The ‘conv.rec’ method has been deprecated, replaced by the
          new ‘traces’ method.

        • The ‘euler.sir’ example has been renamed ‘sir’.

        • The ‘gillespie.sir’ example has been renamed ‘sir2’.

        • The ‘covmat’ method can now be applied to a ‘probed.pomp’
          object.  It returns the estimated covariance matrix of the
          probes.

        • When ‘trajectory’ calls on ‘deSolve’ routines to numerically
          integrate a model vectorfield, more informative error
          messages are generated, and diagnostics are printed when
          ‘verbose = TRUE’.

        • The ‘show’ method applied to pomp objects is now quite terse.
          To obtain detailed information, the ‘spy’ method is
          available.

        • The ‘spy’ method now returns the information formerly
          displayed in a call to ‘show’, in addition to the C files
          associated with any C snippets.

        • The use of ‘$’ methods to access the slots of ‘pomp’ S4
          objects has now been removed.  These classes are no longer
          exported (for the most part).

        • The ‘transform’ argument to the ‘probe.quantile’ function has
          been removed (as it is entirely redundant!).

        • The old and deprecated ‘mif’ and ‘bsmc’ methods have been
          removed.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_9:

        • The ‘obs’ and ‘states’ arguments of ‘simulate’ are deprecated
          and will be removed in a forthcoming release.

        • The C-level interface for ‘apply_probe_sims’ has changed: the
          new argument ‘rho’ must be the “package:pomp” environment.

        • A bug in ‘pfilter’ (and hence ‘pmcmc’) when
          ‘filter.traj=TRUE’ was discovered and fixed.  In the buggy
          version, the filter trajectory was sampled with incorrect
          weights.

        • Timo Voipio contributed a pull request that traps the error
          resulting from ‘sannbox’ being passed a ‘candidate.dist’ that
          is not a function.

        • ‘show’ and ‘print’ methods have been made very terse: they
          simply report on the class of the object in question.  To see
          more detailed information about a ‘pomp’ object, use ‘spy’.

        • New (unexported) ‘solibs<-’ method allows developers of
          packages extending ‘pomp’ to incorporate C snippets into
          object that contain ‘pomp’ objects.

        • New ‘verbose’ option in ‘trajectory’ gives diagnostic
          information from ‘deSolve’ integration routines.  Of course,
          this is pertinent only if the model skeleton is a
          vectorfield.

        • Bug in the display of ‘istate’ when ‘deSolve::ode’ errors has
          been fixed.

        • New ‘hitch’ function facilitates construction of ‘pomp.fun’
          objects from R functions, C snippets, and links to external
          libraries.

        • Native routines needed to access ‘pomp.fun’ objects in C are
          now registered for use by other packages.

        • ‘coef(object) <- NULL’, where ‘object’ is of class ‘pomp’,
          erases any parameters stored in ‘object’.

        • The ‘euler.sir’, ‘gillespie.sir’, ‘blowflies’, ‘ricker’,
          ‘bbs’, ‘dacca’, and ‘rw2’ examples are all now implemented
          using C snippets.

        • A new ‘pomp_defines.h’ header is provided for developers of
          packages that depend on ‘pomp’.

        • Internally, ‘rprocess’ is no longer stored as an R function.
          The use of plugins is now required for the implementation of
          the ‘rprocess’ component.  Currently, there are five plugins
          available: ‘onestep.sim’, ‘discrete.time.sim’, ‘euler.sim’,
          ‘gillespie.sim’, and ‘gillespie.hl.sim’.

        • The new ‘hitch’ function automates the building and linking
          of C snippets and R functions into ‘pomp.fun’s.

        • The handling of ‘dprocess’ has changed.  The ‘onestep.dens’
          plugin is now deprecated and will soon be removed.
          ‘dprocess’ is now specified directly using either a C snippet
          or an R function, in much the same way that, for example,
          ‘dmeasure’ is specified.

        • The old ‘forward’ and ‘inverse’ options for the ‘dir’
          argument of ‘partrans’ have been dispensed with.  The much
          more descriptive options ‘toEstimationScale’ and
          ‘fromEstimationScale’ remain.

        • The C snippet compiling facilities have been thoroughly
          reworked.

        • ‘onestep.dens’ can now take a ‘Csnippet’ specification of the
          process-model transition density.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_8:

        • All inference functions can now take a list in the ‘start’ or
          ‘params’ arguments.

        • When altering parameters in a call to ‘probe’ on a
          ‘probed.pomp’ object, the new parameters were ignored.  This
          bug has been fixed.

        • New ‘spy’ method displays the C snippet file(s) associated
          with a ‘pomp’ object.

        • The long-deprecated ‘seed’ argument to ‘bsmc’ and ‘bsmc2’ has
          been removed.

        • More work to obviate warnings generated by T. Kalibera's
          latest ‘rchk’ checks.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_7:

        • Messages from the compiler resulting from attempts to compile
          C snippets are now suppressed on all platforms except in case
          of failure.  Setting ‘verbose=TRUE’ forces display of these
          messages.

        • Source codes have been revisited to obviate warnings
          generated by T. Kalibera's latest ‘rchk’ checks.

        • Fix a minor bugs in ‘spect’.

        • Improve test coverage.

        • ‘spect.match’ has been refactored, with small changes to the
          interface.

        • ‘pomp’ now handles specification of workhorse functions
          (i.e., ‘rprocess’, ‘dprocess’, ‘rmeasure’, ‘dmeasure’,
          ‘initializer’, ‘skeleton’, ‘rprior’, ‘dprior’,
          ‘fromEstimationScale’, ‘toEstimationScale’) as ‘NULL’ more
          consistently.

        • Fix bug in systematic resampler when ‘np != nw’.

        • Fix bug in ‘conv.rec’ when only one parameter is requested.

        • Correct and improve documentation for ‘conv.rec’.

        • ‘coef<-’ can now take a list of parameters: it simply applies
          ‘unlist’ to turn the list into a numeric vector.

        • Simplify ‘conv.rec’.

        • In ‘pfilter’, ‘Np’ is now a required argument unless ‘params’
          is specified as a matrix of particles.  Thanks to Carles
          Breto for catching the unintended behavior.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_6:

        • The bug reported in issue #57 has been fixed.

        • A bug arising when building pomp objects with Csnippets in
          certain Windows configurations has been fixed.

        • Issue #56, in which covariate names are discarded when
          coercing a pomp object to a data frame, has been fixed.
          Thanks to Eamon O'Dea for reporting this bug.

        • More informative error messages are given when ‘bake’ or
          ‘freeze’ return ‘NULL’.  In such a case, these functions now
          generate a warning and return a character-string message,
          with attributes.

        • Improve documentation of ‘traj.match’, in response to Issue
          #57.

        • A new facility, ‘gillespie.hl.sim’, allows implementation of
          Gillespie's algorithm for exact stochastic simulation of
          continuous-time Markov processes via a streamlined C snippet
          interface.

        • The old facility for Gillespie simulations, ‘gillespie.sim’,
          now accepts C snippets for faster calculation of event rates.

        • The old ‘skeleton.type’ and ‘skelmap.delta.t’ arguments of
          the ‘pomp’ constructor, which have generated error messages
          since version 1.9.2, have been done away with completely.

        • Eamon O'Dea identified a bug (Issue #54) occurring when
          ‘pomp’ is called with a single-row data frame.  This has been
          fixed using his contributed patch.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_5:

        • A new ‘dmultinom’ function is provided in ‘pomp.h’.  This
          provides the probability distribution function for the
          multinomial distribution.

        • Improved tests.

        • Fixed bugs emerging in R-devel due to refactoring of
          underlying R source code.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_4:

        • Eamon O'Dea pointed out that the bug in ‘gillespie.sim’,
          addressed by version 1.12.3, was not completely fixed.  This
          problem has now been resolved.  In addition, covariates are
          now guaranteed to be evaluated at least once per observation
          interval.

        • The new argument ‘hmax’ to ‘gillespie.sim’ allows the user to
          specify the maximum step size that will be taken before
          covariates are evaluated.

        • The K-leap method has been removed.  Its accuracy is low on
          test problems and it is difficult to make it compatible with
          the pomp paradigm.  In particular, it does not readily
          accomodate time-varying covariates in a sensible way, nor
          does it lend itself to simulations at pre-specified times.

        • ‘bspline.basis’ and ‘periodic.bspline.basis’ now take an
          optional non-negative integer argument ‘deriv’.  When ‘deriv
          > 0’, the order-‘deriv’ derivative of each basis function is
          returned.

        • A new function, ‘periodic_bspline_basis_eval_deriv’, has been
          added to the C API.  This function gives access, at the C
          level, to evaluation of the derivatives of periodic
          B-splines.

        • Upgrade license to GPL version 3.

        • Fix buffer-flow problem identified by ‘valgrind’.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_3:

        • Fix bug found by Eamon O'Dea in ‘gillespie.sim’.

        • Fix bug in ‘onestep.sim’.

        • The Ricker example has a new parameter, c, which scales the
          (unobserved) population size.  By default, c=1, so that the
          behavior is as before.

        • Improved error trapping.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_2:

        • Some changes have been made to the use of random numbers in
          some codes (the stochastic simulations in ‘gillespie.sim’ and
          the resampling in the particle-filtering codes).  These
          changes will mean that calculations performed before will not
          be reproducible in perfect detail, but will be statistically
          equivalent.

        • Minor changes in C codes to obviate warnings generated by T.
          Kalibera's ‘rchk’ checks.

        • The rare and fascinating “Bug of St. Patrick” has been fixed.
          Thanks to Carles Breto for finding the bug and helping to
          isolate it.

        • More informative error messages are generated when ‘dmeasure’
          returns a non-finite likelihood in any of the particle
          filtering codes.

        • Some streamlining of codes.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_1:

        • Callable routines are now registered.

        • The functions ‘bake’, ‘stew’, and ‘freeze’ now preserve
          information about the system time used in computation as an
          attribute of the returned object.  In addition, these
          functions store information about the RNG settings.

        • Some documentation improvements, courtesy of Sebastian Funk.

        • Various documentation improvements.

        • More verbosity is provided with ‘verbose=TRUE’.

        • Better handling of ‘pomp’'s ‘times’ argument.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_0:

        • New ‘logLik’ method for ‘pmcmcList’ objects.

        • The deprecated option to supply a matrix or numeric vector as
          the ‘data’ argument to ‘pomp’ have been removed and an error
          is now generated.  ‘data’ must be provided as either a data
          frame or an object of class ‘pomp’.  See ‘?pomp’ for details.

        • The deprecated ‘skeleton.type’ and ‘skelmap.delta.t’
          arguments to ‘pomp’ have been removed.  Using these arguments
          will now generate an error message.  The correct method of
          specifiying the deterministic skeleton is now explained in
          the help pages (‘?pomp’).

        • Source code fixes to eliminate warnings during compilation.

        • Improved test suite.

        • Minor documentation correction.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._9:

        • During particle filtering, when non-finite ‘dmeasure’ values
          are generated, an error is generated and the offending
          parameters, states, data, and time are reported.  In methods
          that use parameter transformations (‘transform=TRUE’), the
          reported parameters were on the transformed (estimation)
          scale, which can be confusing.  The error message now gives
          the parameters on the natural (model) scale.

        • Modified ‘src/ssa.c’ to fix UBSAN errors.

        • C codes have been modified to take advantage of changes to
          the R API (R SVN REVISION 71180).

        • A bug in ‘mif2’ arising when filtering fails in the final
          timestep has been fixed.  In this case, when all particles
          are deemed inconsistent with the data, we use an unweighted
          mean (with a warning) in place of the default weighted mean.

        • C codes have been modified to take advantage of changes to
          the ‘R’ API (R SVN REVISION 71180).

        • Modified ‘src/ssa.c’ to fix UBSAN errors.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._8:

        • There is a new option, ‘shlib.args’, to ‘pomp’.  This allows
          arbitrary options to be passed to the compiler when C
          snippets are used.  In particular, one can link a library of
          C snippets against a precompiled static library.

        • In Sobol' sequence generation (‘sobolDesign’,
          ‘profileDesign’), we now use the suggestion of Joe & Kuo
          (2003) to choose a better sequence start point.

        • The generation of Sobol' sequences (‘sobolDesign’,
          ‘profileDesign’) is now performed using the ‘NLopt’ routines
          written in C instead of the original TOMS 659 FORTRAN codes.
          The copyright notices are located in the source code.

        • The stochastic simulation algorithms underlying the Gillespie
          and K-leap methods (‘gillespie.sim’, ‘kleap.sim’) have been
          refactored in C.  In addition, errors due to accumulation of
          round-off error have been repaired.  The result will be more
          accurate, but somewhat slower when there are a very large
          number of reactions.

        • Fixed a bug in ‘plot’ on ‘pomp’ objects with more than 10
          variables to plot.

        • Refactored ‘rw.sd’ for greater stability.

        • Modified the “dacca” example to use C snippets.

        • Made Sobol' codes more robust.

        • Modified the demos to use best practices.

        • Further improvements to the test suite.  Code coverage is now
          100%.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._7:

        • Improvement of the test suite and of error messages.

        • Improve the ‘show’ and ‘print’ methods for ‘pomp’ objects.

        • Some internal refactoring.

        • Improve error messages for missing basic components.

        • Fix typos in one of the help-page examples.

        • Several obscure bug-fixes.

        • Add some references.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._6:

        • Major revisions to the package help pages and manual.  The
          separate documentation on C snippets and process-model
          plugins has been merged into the main ‘pomp’ help page, which
          now has comprehensive instructions on building a ‘pomp’
          object.

        • Update to the package help page.

        • New methods for the Ensemble Kalman Filter (‘enkf’) and
          Ensemble Adjustment Kalman Filter (‘eakf’) have been added to
          the package.

        • There is a new plugin for ‘rprocess’ called ‘kleap.sim’.
          This implements the so-called “K-leap method” of Cai & Xu
          (2007).

        • Major overhaul of error handling system and to error and
          warning messages.  Many more errors are now trapped and
          reported with more informative messages.

        • The matrix and numeric vector options for the ‘data’ argument
          to ‘pomp’ are now deprecated and will be removed in a future
          release.  In calls to ‘pomp’, ‘data’ should be either a data
          frame or a ‘pomp’-class object.

        • In ‘mif2’, it is now required that ‘Nmif>0’.

        • Redundant ‘bootstrap’ argument to ‘nlf’ has been removed.

        • Many improvements to the test suite to obtain better code
          coverage.

        • Fixed bugs that might arise in rare circumstances in
          ‘simulate’ and ‘eulermultinom’ functions.

        • Fixed a bug in ‘pompExample’.

        • Fixed several small, rare bugs found as a result of improved
          testing.

        • Fixed bug in specification of skeleton in pompExamples.

        • ‘pomp’ is no longer an S4 method.  Its new status as an
          ordinary function abbreviates and consolidates the code and
          simplifies the documentation.

        • A bug restricting access in C code to ‘userdata’ has been
          fixed.

        • Fixed bug in ‘pompExample(...,show=TRUE)’.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._5:

        • A better interface for specifying a model's deterministic
          skeleton is provided.  One specifies
          ‘skeleton=map(f,delta.t)’ for a discrete-time skeleton (a
          map) and ‘skeleton=vectorfield(f)’ for a continuous-time
          skeleton (a vectorfield).  The old arguments ‘skeleton.type’
          and ‘skelmap.delta.t’ are deprecated and will be removed in a
          future release.

        • The ‘pfilter’ help page has been improved.  Specifically, the
          discussion of filtering failures is better.

        • Miscellaneous improvements to the help pages.

        • ‘mif2’ no longer computes filter means.

        • The new argument ‘show’ of ‘pompExamples’ allows one to
          display the example code instead of executing it.

        • The minimum version of R supported is now 3.1.2.

        • ‘init.state’ now has the optional argument ‘nsim’.  Using
          this, one can request multiple initial state vectors per
          parameter vector.

        • ‘pfilter’ now uses less memory when it is asked to run at a
          single point in parameter space.

        • A bug associated with the ‘rw.sd’ argument to ‘mif2’ on
          Windows platforms has been fixed.

        • The ‘method="mif2"’ option to ‘mif’ has been removed.  Use
          ‘mif2’ instead.

        • The ‘particles’ method (rarely if ever used), has been
          removed to streamline the ‘mif’ codes.

        • The ‘method="mif2"’ option to ‘mif’ is now deprecated.  It
          will be removed in a future release.  Use ‘mif2’ instead.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._4:

        • Following the publication of the Journal of Statistical
          Software announcement paper, the ‘CITATION’ has been modified
          to include the appropriate citation.  Please use
          ‘citation("pomp")’ to learn about how to cite ‘pomp’
          correctly.

        • ‘conv.rec’ on the results of a ‘mif2’ computation now play
          nicely with ‘reshape2::melt’.

        • It is now possible to direct ‘pomp’ to place ‘Csnippet’ codes
          in a specified location.  This is accomplished via the new
          ‘cdir’ and ‘cfile’ arguments to ‘pomp’.

        • When several concurrent R processes attempt to simultaneously
          compile ‘Csnipet’ code from copies of a ‘pomp’ object on the
          same machine, a race condition exists.  This release fixes
          this by ensuring that ‘Csnippet’ codes are written and
          compiled in a process-specific directory.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._3:

     This release removes several long-deprecated features.

        • The ‘seed’ argument to ‘pfilter’ has been removed.  Use
          ‘freeze’ to obtain similar functionality.

        • The redundant ‘pars’ argument to ‘mif’ has been removed.
          Names of parameters to be estimated are taken from the
          nonzero entries of ‘rw.sd’.  Initial-value parameters are
          designated using the ‘ivps’ argument.

        • The old ‘parameter.transform’ and ‘parameter.inv.transform’
          arguments to ‘pomp’ have been removed.  They were superseded
          by the arguments ‘fromEstimationScale’ and
          ‘toEstimationScale’ in version 0.65-1.

        • Some internal changes to ‘mif2’ by C. Breto, in support of
          panel methods under development.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._2:

        • Bug fix: for POMPs with a scalar state variable, the
          ‘filter.mean’, ‘pred.mean’, and ‘pred.var’ methods dropped
          the singleton dimension of the respective arrays, in conflict
          with the assumptions of certain ‘plot’ methods.  This
          resolves issue #3.

        • Documentation improvements.  Specifically, the details of how
          step-sizes are chosen in the ‘euler.sim’,
          ‘discrete.time.sim’, and ‘onestep.sim’ plugins has been
          spelled out explicitly.  Also, incompleteness in the
          ‘sannbox’ documentation has been corrected.

        • Provide ‘filter.traj’ method for ‘pmcmcList’ objects.

        • Fixed a bug in ‘mif’ and ‘mif2’ when
          ‘cooling.type="hyperbolic"’ and ‘cooling.fraction.50=1’.

