 Summary of important user-visible changes for statistics 1.9.0:
-------------------------------------------------------------------

 Important Notice: 1) Update dependency to datatypes 1.3.3.
                   2) The 29 probability distribution classes have moved into
                      the `prob` namespace.  The flat class names are gone;
                      this is a rename, not an alias.
                   3) The generalized additive model classes now fit boosted
                      trees by default, as MATLAB does.  Every fitted value,
                      score and loss moves.  The spline engine remains
                      available as 'FitMethod', 'splines'.
                   4) `fitcnet` and `fitrnet` now default to the LBFGS
                      solver, and `fitcnet` to rectified hidden layers and a
                      softmax output.  Every default fit returns different
                      weights.
                   5) Models of the compact classes saved by an earlier
                      version no longer load and must be re-saved from the
                      model they were compacted from.
                   6) Incompatibility with the `nan` package.
                   7) Using `tablicious` as a drop in replacement for
                      `datatypes` might cause issues.

 Breaking changes:
 =================

 This release changes behaviour that working code may depend on.  Each item
 below says what breaks and what to write instead.

 ** anova2:
    NaN values are refused again, as they always were and as MATLAB does.

 ** anovan:
    the returned table has nine columns where it had seven; 'Singular?' is
    inserted at column 4, moving 'Mean Sq.' to column 5, and 'Eta Sq.' and
    'Part. Eta Sq.' are appended at 8 and 9.  A model with any random factor
    keeps the interactions that factor appears in, so `p` and the table are
    longer and the table gains eight further columns; p-values change for
    every random effects model.  An interaction is named 'X1:X2', and the
    random factor marker is no longer carried in the names returned in
    `atab`, `stats.varnames` or the expected mean square expressions.
    Reading the table by name from `atab(1,:)` is unaffected.

 ** boxplot:
    the quartiles are taken from `quantile` at its own default method, the
    one `prctile` and MATLAB use, rather than from core's `statistics`.
    Boxes, whisker fences, the returned statistics matrix and what counts as
    an outlier all move.

 ** ClassificationGAM, RegressionGAM:
    the classes fit boosted trees by default; pass 'FitMethod', 'splines' for
    the previous engine.  Eleven spline options now raise unless that engine
    is selected, and a second output from `RegressionGAM.predict` raises
    under the default engine.  The boosted classifier fits by local scoring,
    so every multi-predictor classification GAM fits to different numbers.  A
    tree leaf now holds at least five observations.  `Interactions` reports
    the K-by-2 matrix of fitted predictor pairs, not the request that was
    passed; use `IntMatrix` to recover the argument.  `ScoreTransform`
    defaults to 'logit' and the raw score is the log-odds pair MATLAB
    reports.  `RegressionGAM.fitBoosted` is no longer a public method.

 ** ClassificationKNN:
    `DistanceWeight` holds the name of the weight rather than a function
    handle, and now applies: nothing read it before, so 'inverse' and
    'squaredinverse' changed no prediction.  The documented spelling
    'squaredinverse' is accepted.

 ** ClassificationSVM:
    `loss` returns different numbers, having scaled every loss by the class
    labels so that only the classification error was right.  `margin` takes Y
    in the form the class labels are in, as documented, where it required the
    +1/-1 coding.  `Alpha` is populated for every kernel and holds unsigned
    magnitudes, `Beta` is the primal coefficient vector for a linear kernel
    only, `SupportVectorLabels` is s-by-1 of +/-1, and `IsSupportVector` is
    logical.  No classification result changes.

 ** cluster, clusterdata:
    'MaxClust' yields exactly N clusters however the merge heights tie, and a
    'Cutoff' on the inconsistency coefficient requires every node below to be
    under the cutoff.  Both returned too few clusters.

 ** ClusterCriterion, CalinskiHarabaszEvaluation, DaviesBouldinEvaluation,
    GapEvaluation, SilhouetteEvaluation:
    the cluster evaluation classes are value classes, not handles, so `e2 =
    e1` copies; assign results back, as `e = addK (e, 4)`.
    `ClusterCriterion` is abstract and can no longer be constructed directly.

 ** CompactClassificationSVM:
    the class drops `IsSupportVector`, which was sized to the training set
    and which MATLAB's compact class does not carry.

 ** cvpartition:
    `test` and `training` return one column per requested set; given a vector
    of set indices they returned one column per set per pass.

 ** evalclusters:
    a matrix of clustering solutions with no `KList` is numbered by the
    clusters each column holds, not by column position, so criterion values
    and `OptimalK` change.  `SilhouetteEvaluation.ClusterSilhouettes` holds
    the mean silhouette of each cluster rather than every observation's
    value.

 ** factoran:
    the function is rewritten and its output signature is now MATLAB's,
    `[lambda, psi, T, stats, F]`.  The third output was the factor scores and
    is now the rotation matrix; scores moved to the fifth, so code taking the
    third output as scores silently receives an m-by-m matrix.  The fit is
    maximum likelihood by default where it was principal axis factoring,
    which remains available as 'Extraction', 'paf'.

 ** fcnntrain, fcnnpredict:
    both take activation names in two arguments, `Activations` and
    `OutputLayerActivation`, rather than numeric codes in a single vector.
    `fcnnpredict` takes the layer weights and biases, not the model structure
    `fcnntrain` returns.  The `Alpha` argument and field are removed.  The
    'elu' activation saturates at -1, as it is defined to, where its negative
    arm carried the leaky rectifier's 0.01 scale.

 ** fitcnet:
    'Solver' defaults to 'lbfgs', MATLAB's solver, where it defaulted to
    'sgd', so every default fit returns different weights.  'LearningRate'
    belongs to the epoch loop and now raises unless a solver is named, while
    'GradientTolerance', 'LossTolerance' and 'StepTolerance' are now accepted
    by default; `TrainingHistory` and `ConvergenceInfo` carry the fields of
    the solver that ran.  `fitrnet` is new in this release.  `fitcnet`
    additionally defaults 'Activations' to 'relu', 'OutputLayerActivation' to
    'softmax' and 'LearningRate' to 0.003.  Initial weights are drawn from
    Octave's generator, so repeated fits no longer return an identical model
    and `rand ('seed', s)` governs a fit.  `ConvergenceInfo` reports the
    value the fit ended at as a scalar and carries the series beside it as
    `History`.  `ModelParameters` reports the fit rather than the network;
    read `Mdl.LayerWeights` and `Mdl.LayerBiases`.

 ** fitdist:
    the 'theta' option defaults to 0 for the generalized Pareto, as MATLAB
    assumes it, where it defaulted to 1; `mle` changes with it.

 ** fpdf:
    the density at x = 0 is 1 at df1 = 2 and Inf below it, where it was zero
    whatever the numerator degrees of freedom.

 ** friedman:
    the second output is a cell array with a header row, as MATLAB's is and
    as `anova1` and `anova2` already were; read `tbl{2,2}` rather than
    `tbl.SS(1)`.  The table is displayed by default.

 ** gpfit:
    the second argument is `alpha`, the confidence level, not `theta`, a
    known location; `paramhat` is 1-by-2 and `paramci` 2-by-2.  Fit a known
    location by shifting the data.  Note `gpfit (x, 0.05)` was a fit at
    location 0.05 and is now a 95% confidence level.

 ** gplike:
    `params` is the two element vector [k, sigma] and `acov` is 2-by-2, where
    it was 3-by-3 with a zero row and column.

 ** hmmviterbi, hmmestimate:
    `hmmviterbi` returns the true maximum probability path, having scored a
    spurious transition out of the last state, and `hmmestimate` no longer
    counts a phantom transition out of an assumed initial state.  Both return
    different values.

 ** LinearModel:
    a weighted fit's `LogLikelihood` carries the 0.5 * sum (log (w)) term and
    counts only nonzero weight observations, following R rather than MATLAB;
    `AIC`, `AICc`, `BIC` and `CAIC` move with it.  Unweighted and robust fits
    are unchanged.

 ** LinearModel:
    `Formula` is a `LinearFormula` object rather than a structure or a
    character vector.  Term order follows the variable order of the data
    rather than the alphabetical order of their names, and no longer depends
    on the order the formula names them, so coefficient names move with it.
    The omitted reference level of a character or string grouping column is
    the level the data presents first, not the alphabetically first one, so
    coefficients change name and meaning; a categorical column is unaffected.
    A model with no intercept and a categorical predictor gives the first
    categorical an indicator for every level by both routes, so its
    coefficients are the group means; this is a deliberate deviation from
    MATLAB, which drops the reference level.

 ** mle:
    the 'normal' and 'lognormal' distributions return the maximum likelihood
    estimate, `std (x, 1)`, where they returned the unbiased `std (x, 0)`.

 ** nbinfit:
    the confidence bounds are no longer clamped to the parameter space, a
    bound outside it being what tells the caller the normal approximation has
    broken down.

 ** negloglik:
    the distribution object method returns the negative log likelihood, as
    documented and as MATLAB returns it; it returned the log likelihood, the
    wrong sign.

 ** pca:
    `tsquared` is 0 where the fit has one degree of freedom or fewer, and NaN
    for dropped rows, returned at the full observation count.

 ** prob distribution objects:
    the 29 classes are now `prob.NormalDistribution` and so on; the flat
    names are gone, so `class (pd)` and `isa (pd, ...)` take the qualified
    name.  `makedist`, `fitdist`, `cdf`, `pdf`, `icdf`, `random` and `mle`
    take the distribution's name and are unaffected.  `DistributionName`
    holds the distribution's name ('Normal'), not the class name.
    `prob.WeibullDistribution` renames `lambda` and `k` to `A` and `B` and
    `prob.RayleighDistribution` renames `sigma` to `B`.  `ParameterValues` is
    a cell for the piecewise linear and multinomial classes, `x` and `Fx` of
    the piecewise linear class are rows, and the 29 classes now share an
    abstract base, `prob.ProbabilityDistribution`, as MATLAB's do.

 ** proflik:
    the distribution object method computes a true profile likelihood, re-
    maximizing over the remaining parameters at each point, where it held
    them fixed at their fitted values and so gave wrong results for every
    multi-parameter distribution.  The default grid is 101 values over the
    98% confidence interval when the selected parameter is the only one
    estimated, and 21 otherwise.

 ** regress_gp:
    the prediction intervals were wrong in both branches and are now correct,
    and both branches return the lower bound in column 1; code reading
    Yint(:,1) as an upper bound must be changed.

 ** signrank:
    two differences agreeing to within eps (x) + eps (y) rank as tied and one
    smaller than that is dropped, as MATLAB does, so `signedrank`, `zval` and
    the p-value move on such data.  `stats` carries `signedrank` where it
    carried `sign`, which belongs to `signtest`, and `zval` is empty for the
    exact test.

 ** signtest:
    the test decision `h` is returned as a logical, as documented and as
    MATLAB returns it, where it was a double.

 ** tabulate:
    the percentage column is count / total * 100 taken literally, so data
    with no observations gives NaN where it gave zero.

 ** The compact classes:
    `CompactClassificationSVM` drops `ModelParameters` and `IsSupportVector`,
    `CompactClassificationNeuralNetwork` drops six properties describing the
    fit, and `CompactClassificationGAM` drops seven, MATLAB's own compact
    classes carrying none of them.  Read any of them off the model that was
    compacted from.  A compact SVM, neural network or GAM model saved by an
    earlier version therefore no longer loads, and `loadmodel` raises
    'invalid model'.  The compact regression and Gaussian process classes are
    new in this release and never carried them.

 ** The distribution functions:
    the 130 *cdf, *pdf and *inv functions validate the class of their numeric
    arguments.  Continuous distributions and every *inv accept double and
    single only; the discrete *cdf and *pdf additionally accept the integer
    types and promote to double, so the result is always a probability.
    Logical and character arrays are rejected.  This fixes silently wrong
    answers: `geocdf (int32 (0:4), 0.3)` returned [0 1 1 1 1], `nbincdf`
    returned zeros and `binopdf` returned Inf.

 ** The random generators:
    the 39 generators and the distribution objects' `random` method treat a
    negative dimension as zero and return an empty array, as core Octave and
    MATLAB do, instead of raising.

 ** The supervised learner classes:
    `ScoreTransform` and `ResponseTransform` hold the name of the transform
    rather than a function handle, so `strcmp (Mdl.ScoreTransform, 'none')`
    works and `predict` applies the transform for you.  `Prior` is a 1-by-K
    row in `ClassNames` order.  `W` weighs each class by its prior rather
    than being uniform.  An observation is dropped only for a missing
    response, so `size (X, 1)`, `numel (W)` and `NumObservations` now agree
    and `RowsUsed` is empty when nothing was dropped.  The `Standardize`
    property is gone from eleven classes; test `! isempty (Mdl.Mu)` instead.
    `Cost` refuses anything that is not a square matrix.  `BinEdges` is a
    cell on the cross-validated classifier, and a column cell on the GAM
    classes.  `RowsUsed` is a logical mask on `ClassificationGAM`,
    `ClassificationSVM` and `RegressionGAM`, where it was a double.  `edge`
    normalizes its 'Weights' within each class to that class's prior.  The
    cross-validated models are read only apart from `Cost`, `Prior` and the
    transforms, either assignment now reaching every fold, and their
    transforms are applied where they used to be inert.
    `CrossValidatedModel` holds the learner's short name, not the class name.
    An observation that no fold held out gets a missing label with NaN
    scores, a deliberate deviation from MATLAB, which names the first class.

 ** tiedrank:
    an array is ranked along its first dimension, as MATLAB does, instead of
    being refused; `tieadj` carries one entry per column.

 ** trimmean:
    a non-scalar percentage is refused, as in MATLAB; it was accepted and
    returned an untrimmed mean behind a warning.

 ** ttest, ttest2:
    `Alpha` is validated; a negative, zero, unit or vector value was
    accepted, a negative one returning a NaN confidence interval together
    with 'do not reject'.

 ** unifit:
    the function returns MATLAB's four outputs [ahat, bhat, aci, bci], where
    it packed both estimates into one vector and both intervals into one
    matrix.  X may now be a matrix, negative data is accepted, and the upper
    endpoint's interval was inverted.

 New functions:
 ==============

 ** andrewsplot:
    Andrews plot of multivariate data, with grouping, four standardizations
    and a quantile mode.

 ** ansaribradley:
    Ansari-Bradley test for equal dispersions, with an exact permutation
    p-value or a tie corrected normal approximation.

 ** biplot:
    biplot of principal component coefficients or factor loadings.

 ** ClassificationDiscriminant.cvshrink:
    cross-validate the discriminant over a grid of `Gamma` and optionally
    `Delta`.

 ** ClassificationDiscriminant.mahal, ClassificationDiscriminant.logp,
    ClassificationDiscriminant.nLinearCoeffs:
    squared Mahalanobis distance to each class mean, the log of the density
    summed over the classes, and the number of predictors kept at a
    regularization threshold; also on the compact class.

 ** ClassificationGAM.addInteractions, RegressionGAM.addInteractions:
    fit interaction terms onto a model that already carries its univariate
    ones.

 ** ClassificationGAM.resume, RegressionGAM.resume:
    add trees to a fitted model, continuing in the phase that ran last.

 ** ClassificationPartitionedLinear, ClassificationPartitionedKernel,
    RegressionPartitionedLinear, RegressionPartitionedKernel:
    the cross-validated counterparts of the linear and kernel learners.

 ** ClassificationPartitionedModel.kfoldLoss,
    ClassificationPartitionedModel.kfoldMargin,
    ClassificationPartitionedModel.kfoldEdge:
    the class had none of the three; `kfoldLoss` takes 'classiferror',
    'classifcost', 'mincost' or a function handle, the margin based losses
    not being offered.

 ** CompactLinearModel:
    a fitted linear model without its training data, returned by
    `LinearModel`'s new `compact` method.

 ** CompactRegressionGAM:
    the compact counterpart of `RegressionGAM`.

 ** copulastat, copulaparam, copulafit:
    complete the copula family, which already shipped `copulacdf`,
    `copulapdf` and `copularnd`.

 ** coxphfit:
    Cox proportional hazards regression, opening survival analysis, with
    stratified models, the counting process form and seven residual types.

 ** dbscan:
    density-based spatial clustering of applications with noise.

 ** discardSupportVectors:
    empty the support vectors of a linear kernel model and leave `Beta` and
    `Bias` to predict, on the four SVM classes; the engine's own copy is
    collapsed, so the memory is freed.

 ** dwtest:
    Durbin-Watson test for autocorrelation in regression residuals, with an
    exact p-value by Imhof's method.

 ** ecdfhist:
    histogram built from the output of `ecdf`.

 ** fitckernel, ClassificationKernel, fitrkernel, RegressionKernel:
    Gaussian kernel models for large data, fitted linearly in a randomized
    feature space, with `resume`.

 ** fitclinear, ClassificationLinear, fitrlinear, RegressionLinear:
    linear models for data with many predictors, with ridge or lasso
    penalties and six solvers; a vector 'Lambda' fits one model per strength
    inside a single object, narrowed afterwards by `selectModels`.

 ** fitcnb, ClassificationNaiveBayes, CompactClassificationNaiveBayes:
    naive Bayes classification with the 'normal', 'kernel', 'mvmn' and 'mn'
    predictor distributions, mixable one per predictor.

 ** fitcox, CoxModel:
    the Cox proportional hazards model as an object, with `survival`,
    `hazardratio`, `coefci`, `linhyptest`, `plotSurvival` and
    `discardResiduals`.

 ** fitglm, GeneralizedLinearModel:
    generalized linear regression as a fitted model object over five
    families, the GLM counterpart of `fitlm` and `LinearModel`.  A binomial
    response given with 'BinomialSize' is the number of successes, as MATLAB
    reads it, and `predict` returns the probability of success.

 ** fitglme, GeneralizedLinearMixedModel:
    generalized linear mixed effects models by penalized quasi-likelihood,
    with four fit methods.

 ** fitlme, fitlmematrix, LinearMixedModel:
    linear mixed effects models from a Wilkinson formula extended with random
    effects terms or from design matrices, by maximum likelihood or REML.

 ** fitnlm, NonLinearModel:
    nonlinear regression by iterative least squares as a fitted model object,
    with an error model and robust fitting.

 ** fitrgp, RegressionGP, CompactRegressionGP:
    Gaussian process regression with ten covariance functions, four explicit
    bases, and `postFitStatistics`.

 ** fitrnet, RegressionNeuralNetwork, CompactRegressionNeuralNetwork:
    neural network regression against the mean squared error with an identity
    output layer.

 ** fitrsvm, RegressionSVM, CompactRegressionSVM:
    support vector machine regression by epsilon-insensitive loss, with
    'SVMtype', 'nu_svr' as an Octave extension.

 ** gamtrain, gampredict, gamboosttrain, gamboostpredict, gamboostpairs,
    gamboostinter, __lbfgs__, __bhtsne__, __knnselect__, __knnbrute__:
    new compiled functions: the spline and boosted-tree GAM engines, the
    limited-memory BFGS solver, the Barnes-Hut t-SNE summation and the
    nearest-neighbour kernels.  They are not meant to be called directly.

 ** glyphplot:
    star glyph plot of multivariate data; Chernoff faces are not supported.

 ** gplotmatrix:
    matrix of grouped scatter plots, with grouped histograms on the diagonal.

 ** hmmdecode:
    posterior state probabilities of a hidden Markov model by a scaled
    forward-backward recursion.

 ** hmmtrain:
    maximum likelihood estimation of hidden Markov model parameters by Baum-
    Welch or Viterbi training.  Baum-Welch is verified bit-for-bit against
    MATLAB; Viterbi training carries two documented deviations.

 ** iforest, IsolationForest:
    isolation forest anomaly detection, with an `isanomaly` method.

 ** invpred:
    inverse prediction from a simple linear regression, with Fieller
    confidence bounds that need not be finite.

 ** jbtest:
    Jarque-Bera hypothesis test of composite normality.

 ** johnsrnd:
    random arrays from the Johnson system of distributions.

 ** KernelDistribution:
    nonparametric kernel smoothing distribution object, created by `fitdist
    (x, 'Kernel')`.

 ** kfoldfun:
    apply a function across the folds of a cross-validated model, on
    `ClassificationPartitionedModel` and `RegressionPartitionedModel`.

 ** kmedoids:
    k-medoids clustering, with the 'pam' and 'small' algorithms.

 ** ksdensity:
    kernel smoothing density estimate, with four kernels, five output
    functions and bounded support; 'Censoring' is not yet implemented.

 ** lasso, lassoglm:
    lasso and elastic net regularized regression by cyclic coordinate
    descent, for least squares and for the five GLM families, with cross-
    validation and the 1-SE rule.

 ** lillietest:
    Lilliefors composite goodness of fit test for the normal, exponential and
    extreme value families.

 ** LinearFormula:
    model formula object, the class of the `Formula` property of a
    `LinearModel` and of a `GeneralizedLinearModel`.

 ** LinearModel.plot, LinearModel.plotInteraction, LinearModel.anova,
    LinearModel.step, LinearModel.compact:
    five new methods.

 ** lof, LocalOutlierFactor:
    local outlier factor anomaly detection, with an `isanomaly` method.

 ** mdscale:
    nonclassical metric and nonmetric multidimensional scaling over five
    stress criteria.

 ** mlecov:
    asymptotic covariance matrix of maximum likelihood estimators, from the
    observed Fisher information.

 ** mnrval:
    predict category probabilities and confidence bounds from a multinomial
    logistic regression model, the companion to `mnrfit`.

 ** mvksdensity:
    multivariate product-kernel smoothing density estimate.

 ** mvregress, mvregresslike:
    multivariate linear regression by maximum likelihood, with three
    algorithms for missing responses.

 ** nanvar, nanstd, nanmedian, nancov:
    complete the nan* family alongside the existing `nanmean`, `nansum`,
    `nanmax` and `nanmin`.

 ** nlinfit, nlparci, nlpredci:
    Levenberg-Marquardt nonlinear least squares with a numeric Jacobian, and
    confidence and prediction intervals for its coefficients and predictions.

 ** nnmf:
    nonnegative matrix factorization, by alternating least squares or
    multiplicative updates.

 ** ocsvm, OneClassSVM:
    one-class support vector machine anomaly detection, with an `isanomaly`
    method.

 ** parallelcoords:
    parallel coordinates plot of multivariate data.

 ** paretotails:
    piecewise distribution object with generalized Pareto tails and an
    empirical middle; the 'kernel' middle segment is not supported.

 ** partialcorr, partialcorri:
    linear and rank partial correlation coefficients, with p-values.

 ** pearsrnd:
    random arrays from the Pearson system of distributions.

 ** perfcurve:
    ROC and other classifier performance curves, returning the curve,
    thresholds, AUC and optimal operating point, with bootstrap bounds.

 ** ppca:
    probabilistic principal component analysis, handling missing data by
    expectation-maximization.

 ** probplot:
    probability plot of a sample against eight reference distributions, with
    censoring and frequency weights.

 ** RegressionPartitionedModel:
    the regression counterpart of `ClassificationPartitionedModel`, returned
    by `crossval` on a `RegressionGAM`, `RegressionGP`,
    `RegressionNeuralNetwork` or `RegressionSVM`.

 ** rica, ReconstructionICA:
    reconstruction independent component analysis for feature extraction,
    with a `transform` method.  `Mu` and `Sigma` are columns and `FitInfo`
    carries the whole minimisation history, as in MATLAB.

 ** robustcov:
    robust multivariate covariance and mean estimate, with the 'fmcd' and
    'ogk' methods; 'olivehawkins' is not implemented.

 ** robustfit:
    robust M-estimator linear regression by iteratively reweighted least
    squares, with nine weight functions.

 ** rocmetrics:
    receiver operating characteristic metrics object, with per-class AUC and
    the `addMetrics`, `average` and `plot` methods.

 ** rotatefactors:
    rotate a factor loading matrix by the orthomax family, promax, or
    procrustes rotation, the last defaulting to 'Type', 'oblique' as in
    MATLAB.

 ** scatterhist:
    scatter plot with marginal histograms or kernel densities.  As in MATLAB,
    the marginal bars point toward the scatter by default and 'Location'
    names the corner the histograms occupy, not the scatter.

 ** sparsefilt, SparseFiltering:
    sparse filtering for feature extraction, with a `transform` method.

 ** spectralcluster:
    spectral clustering using the eigenvectors of a similarity graph
    Laplacian.

 ** StableDistribution, stblpdf, stblcdf, stblinv, stblrnd, stblfit,
    stbllike:
    the stable distribution in the Nolan S0 parameterization, by numerical
    inversion of the characteristic function; `makedist ('Stable')` was
    previously an unsupported stub.

 ** statset, statget:
    the options structure pair used across the package's iterative
    algorithms; seven functions documented an 'Options' argument and nothing
    could build one.

 ** stepwiseglm:
    fit a `GeneralizedLinearModel` by stepwise term selection, with the
    selection trace in its `Steps` property.

 ** stepwiselm:
    stepwise linear regression over five criteria, with term hierarchy
    enforced on both addition and removal.

 ** The classification margin and edge surface:
    fifteen new methods complete it: every full classifier now has `margin`,
    `edge`, `resubPredict`, `resubMargin`, `resubEdge` and `resubLoss`, and
    every compact classifier has `margin` and `edge`.  A compact classifier
    gets no resubstitution method, as in MATLAB.

 ** tsne:
    t-distributed stochastic neighbor embedding, with the 'exact' and
    'barneshut' algorithms.

 Improvements:
 =============

 ** anova:
    the `anova1`, `anova2` and `anovan` backends all run silently, so fitting
    never prints a table or opens a figure.  `varianceComponent` no longer
    returns an interval for a negative variance estimate, and a saturated
    model reports its error term as zero on zero degrees of freedom rather
    than producing no F-ratios at all.

 ** anova1:
    `p` and `F` are NaN for a design with no variation at all and `p` is 0
    where the fit is exact, both having been the wrong way round.  A
    categorical level that no observation uses leaves every field of `stats`,
    so they can be indexed together; this is a deliberate deviation from
    MATLAB, whose own fields disagree in length there.  The `vartype`
    argument is documented as an Octave extension.

 ** anovan:
    the table reports a 'Singular?' flag and the degrees of freedom that can
    actually be estimated for each term.  A design that is not of full column
    rank now takes the minimum-norm least squares solution, where the
    coefficients came from a triangular solve of a singular system and the
    sums of squares were nonsense.  A continuous factor raised to a power is
    squared from the raw predictor rather than the centred one, which could
    put Type II and Type III out by orders of magnitude.  `stats.termcols`
    counts one column per level, and 'sstype' accepts 'H' beside 'h'.

 ** boxplot:
    a single observation, an entirely missing variable and an empty input are
    plotted rather than failing inside the function, integer observations are
    accepted, and a grouped plot with a one-observation group no longer
    fails.

 ** canoncorr:
    rank deficient input was solved against a singular triangular factor, so
    the coefficients ran away and the canonical correlations came back wrong
    with nothing said.  The factorisation now pivots, deficient columns are
    dropped, and a warning is raised as MATLAB raises one.

 ** ClassificationDiscriminant, CompactClassificationDiscriminant:
    all six discriminant types are available where only 'linear' was.
    `DiscrimType`, `Gamma` and `Delta` may be assigned after fitting, re-
    deriving `Sigma`, `LogDetSigma` and `Coeffs` without refitting, and
    `Delta` now eliminates predictors, the new `DeltaPredictor` reporting the
    value at which each drops out.  `predict` applies the `ScoreTransform`
    the model holds, where it ignored it entirely.  Assigning `Prior` or
    `Cost` no longer destroys the model, `LogDetSigma` is accurate on nearly
    collinear predictors, and the class can be loaded at all, `load_model`
    having raised 'invalid model' whatever the model held.

 ** ClassificationGAM, CompactClassificationGAM:
    'Interactions' given as 'all' or as a count built no interaction term at
    all.  Assigning `Cost` was refused on every model.  `ClassNames` keeps
    the type of Y, where it was a cell of character vectors whatever the
    response was.  A numeric response coded 1 and 2 gave a NaN intercept and
    every score with it.  `predict` applies the `ScoreTransform`, which was
    documented, settable and read by nothing.

 ** ClassificationKNN:
    `NumNeighbors`, `Distance`, `DistanceWeight`, `BreakTies`, `IncludeTies`
    and `DistParameter` may be assigned after fitting and are live.
    `predict` applies the score transform once rather than once per query
    row, and its third output honours the cost matrix where it returned 1 -
    posterior.  A model fitted with any metric a kd-tree cannot search could
    not be reloaded; eight of the twelve metrics were affected.  'CacheSize'
    is carried for compatibility.

 ** ClassificationNeuralNetwork:
    the trained parameters are reachable through `LayerWeights` and
    `LayerBiases`; before this a network could be trained with no way to see
    what it had learned.  `loss` accepts every loss MATLAB documents for the
    class and defaults to 'mincost'.  A saved model came back carrying
    another model's numbers, `savemodel` having written 21 of 29 properties
    into a placeholder object.

 ** ClassificationPartitionedModel:
    an explicit `Prior` reached no fold on the discriminant, SVM and neural
    network backings, and a non-default `Cost` reached no fold on the SVM
    backing, which enters it into the box constraint.  A standardized
    `ClassificationKNN` refitted every fold on the raw scale.  `kfoldPredict`
    discarded the predictions of a 'Holdout' partition, raised for a GAM
    backing and refused a cost for a network backing.  The class gains `W`
    and a `disp` of its own, and takes a `Prior` on a naive Bayes backing.

 ** ClassificationSVM, CompactClassificationSVM:
    `predict` and `resubPredict` return the expected cost as a third output,
    and `kfoldPredict` does for an SVM-backed cross-validated model, where it
    raised.  MATLAB returns the cost matrix read transposed; we return the
    row, which is documented.  `resubLoss` returned the wrong number or none,
    and `resubPredict` selected the training rows with a bare mask, so a
    three-predictor model was asked about a single column.  The classes
    report `Prior`, `Cost`, `W`, `CategoricalPredictors` and
    `ExpandedPredictorNames`.

 ** crossval:
    the partition covers only the observations actually trained on; with any
    missing value present each fold trained on rows its own fit then
    discarded.  A function handle over a predictor and a response is no
    longer rejected, the last data variable having been dropped, which is why
    `plsregress`'s 'CV' never worked.

 ** cvpartition:
    'Stratify' and 'GroupingVariables' can be combined, and
    'GroupingVariables' applies to 'Holdout' and 'Leaveout' as well as
    'KFold', where all three accepted it and silently ignored it, giving the
    caller the leakage the option exists to prevent.  A scalar SVAL to
    `repartition` never worked, and seeding is now confined to the call.

 ** evalclusters:
    the returned object has MATLAB's shape and reports MATLAB's names.  The
    silhouette criterion honours the 'Distance' it is given, where it always
    used 'sqeuclidean' and every metric returned the same numbers.

 ** ExhaustiveSearcher, KDTreeSearcher, hnswSearcher, knnsearch, rangesearch:
    the exhaustive search no longer forms the whole distance matrix for the
    four Minkowski-family metrics, and the searches take their K smallest by
    partial selection: a 4000-point self-search at K = 5 falls from 4.5 s to
    1.9 s and searches that could not allocate now run.  The kd-tree search
    is about five times faster, resolving the metric once per query.
    `knnsearch` and `rangesearch` accept a per-call metric.  Asking for more
    neighbours than the data holds is answered with all of them.  Single data
    stays single and every other class converts to double, which fixes
    integer data silently rounding each coordinate difference.  Raising
    `SearchSetSize` on `hnswSearcher` returned the same neighbour for every
    query past a threshold.

 ** fcnntrain, fcnnpredict:
    every network the package trained descended the wrong gradient: the mean
    squared error layer differentiated sum (y - t)^2 as 2y - t rather than 2
    (y - t), so training settled at 2y = t and the network converged on half
    its target.  The backward pass of a hidden activation layer recovered the
    incoming gradient by dividing by its own input, read past the end of the
    array for any widening network, and applied the wrong local derivative
    for six of the eight activations.  The `Accuracy` and `Loss` vectors
    described no network that ever existed and were then stored behind as
    many zeros as the epoch count.  Training visited the samples in a fixed
    order, so with sorted labels the weights swung between the classes
    instead of settling.  Weights are drawn on a range set by the fan-in
    rather than always on [-1, 1].

 ** fitcgam, fitrgam:
    nine new boosted-tree options matching MATLAB in name and default, and an
    interaction asked for by count or 'all' is chosen by testing each
    candidate pair against the predictor phase's residuals and ranking by
    p-value, with 'MaxPValue' setting the cut.  The GAM classes report
    `FitMethod`, `TreeModel`, `ReasonForTermination`, `BinEdges` and
    `PairDetectionBinEdges`, and `ModelParameters` reports MATLAB's thirteen
    fields under the boosted-tree engine.

 ** fitcnet:
    'Prior' and 'Cost' are accepted, having been rejected as unknown
    parameters, so there had been no way to weigh the classes at all.
    'Activations' accepts 'none', which the documentation listed and the code
    rejected.  A model fitted with 'Standardize' set to true was trained on
    the raw predictors while `predict` standardized its own, so
    resubstitution accuracy on a badly scaled problem was 0.275 and is now
    0.925.

 ** fitcsvm:
    a model fitted with 'Standardize' set to true was trained on the raw
    predictors while `predict` standardized its own, so resubstitution
    accuracy on a badly scaled problem was 0.500, chance, and is now 0.912.

 ** glmfit:
    the returned coefficient vector was clobbered by the binomial Anscombe
    residual computation, returning garbage coefficients whenever the `stats`
    output was requested and taking `glmval`'s confidence intervals with it.

 ** glmval:
    accept a numeric 0 or 1 for the 'simultaneous' option and 'BinomialSize'
    as an alias for 'size'.

 ** gpfit:
    the boundary warnings say which boundary was reached and that the
    confidence intervals are withheld.  NaN and Inf observations propagate
    into the estimates rather than being dropped with a warning.

 ** hygecdf, poisstat, wblpdf, ClassificationNeuralNetwork:
    error messages and help text corrected: `hygecdf` named its third
    argument `k` where `hygepdf` names it `M`, `poisstat` named SIGMA,
    `wblpdf`'s three signature lines named `wblinv`, and the `Solver`
    property read 'Gradient Descend'.

 ** LinearModel, fitlm:
    a robust fit reported the wrong `LogLikelihood` and information criteria,
    and a robust fit given weights scored the wrong residuals, so a precisely
    measured observation was less likely to be downweighted.  A variable the
    model does not use is no longer counted as one of its predictors.
    `Steps` is populated by `stepwiselm` and `step`, where it was always
    empty.  `removeTerms` could not name a term on a table model whose
    formula uses only some of the table's variables, `step` refused any model
    holding a power term, and `stepwiselm` silently dropped one from a
    starting model or bound.  Thresholds letting a term enter and leave at
    once are refused, where the search never returned.  `VariableNames` and
    `PredictorNames` are column cell arrays.

 ** mle:
    the custom distribution interface is implemented, having been a stub that
    printed a message and silently fitted a normal.  The 'bernoulli' and
    'unif' families could not be fitted at all, and an empty 'Frequency'
    raised instead of meaning no frequencies.

 ** mnrfit:
    rewritten for MATLAB compatibility: nominal models with any number of
    categories, having errored for more than two, plus ordinal and
    hierarchical models, four links, the full `stats` structure and the
    `EstDisp` option.

 ** ModelParameters:
    the property reaches its final shape on every learner that has one.
    `ClassificationKNN` and `ClassificationDiscriminant` gain it, having been
    the only learners without one; the neural network pair reports the fit as
    it was asked for rather than the network that came out of it;
    `RegressionGP` reports its starting values; and the six partitioned
    classes report the learner's parameters under their own tags.

 ** optimalleaforder:
    a custom 'Transformation' is reachable, having been documented and
    implemented but refused before the code that uses it ran, and a two-leaf
    tree no longer crashes.

 ** paramci, proflik:
    `paramci` reports one column per parameter on `BinomialDistribution`,
    holding the fixed N at its own value, which also unblocks `proflik`
    there, and a fixed parameter is addressable by name again on every
    distribution.  `proflik` returns a third output, defaults `pnum` to the
    first free parameter, keeps the profiled-out parameters inside their own
    range, and refuses a parameter with no confidence interval.  On
    `BurrDistribution` it profiled a censored likelihood, the frequencies
    having landed in the censoring slot.

 ** pca:
    three defects in the handling of missing data and weights, contributed by
    Swayam Shah (GitHub PR #451).  With 'Rows' set to 'all' the guard that
    refuses NaN input fired only when every column held a NaN.

 ** pdist, pdist2:
    no longer return a negative distance: 'cosine', 'correlation' and
    'spearman' put a row at -2.2e-16 from itself.

 ** prob.PiecewiseLinearDistribution:
    `mean`, `var` and `std` of a truncated distribution are computed exactly
    segment by segment, where quadrature integrated across the density's
    jumps and lost four to five digits.

 ** randsample:
    added to the package INDEX, so the function is listed in `pkg describe`
    and the online documentation; it shipped but was undiscoverable there.

 ** regress:
    the coefficient standard errors and confidence intervals are computed
    from the QR factor directly rather than by inverting R' * R, which
    squared the condition number of the design.  On the Longley benchmark
    they now match the NIST certified values to 6e-13 relative, previously
    2e-8, with no spurious singularity warning.

 ** regression_ftest, regression_ttest:
    `regression_ttest` had no working call form, `cov` of two vectors
    returning a matrix, and its fitted values were evaluated at mean (x)
    instead of at x, so the residual sum of squares was really the total.
    `regression_ftest` refused the commonest test of all, dropping a single
    predictor.  Positive tests have been added to both.

 ** RegressionGAM:
    `predict` computes ySD and yInt from the model's own terms rather than
    the stored predictors, so a model built with 'Interactions' or a
    'Formula' no longer reports a standard deviation several times too large,
    or raises.  A single Inf passed validation, and a scalar 'Knots', 'Order'
    or 'DoF' was never expanded.  `savemodel` wrote a text file where every
    other class writes a binary one.

 ** RegressionGAM, ClassificationGAM:
    the spline fitting is compiled and each predictor's design is factorised
    once for the whole fit: fitting a classifier is four times faster and
    cross-validating one between five and nine times.  A rank deficient
    design no longer divides by a singular value that is rounding noise.

 ** sampsizepwr:
    the 'r' test type for the correlation coefficient was unreachable by any
    route, and the sample size came from Fisher's transformation of the
    difference between the two correlations, which is right only when the
    null correlation is zero, the single value the function refused.

 ** slicesample:
    a log density supplied through 'logpdf' was logged a second time, so the
    chain sampled an entirely different distribution without complaint;
    drawing from a standard normal returned values with a mean around -8000.
    Three missing input checks are added.

 ** svmpredict:
    scoring a single observation corrupted the heap and aborted the
    interpreter; two or more rows were fine.  The result pointers referred to
    a temporary that was freed before the prediction loop wrote to it.

 ** The copula family:
    `copulapdf` gains the Gaussian and Student's t families and `copularnd`
    the Frank and Gumbel-Hougaard families, so every family MATLAB supports
    now works in every copula function; only Clayton previously worked in all
    five.  The Ali-Mikhail-Haq and Farlie-Gumbel-Morgenstern Octave
    extensions work throughout as well.

 ** The distribution name wrappers:
    `cdf`, `pdf`, `icdf`, `random`, `makedist`, `fitdist` and `mle` accept
    the same set of distribution names, matched ignoring case, spaces and
    hyphens; they previously accepted disjoint spellings, so `makedist
    ('Extreme Value')` and `cdf ('ExtremeValue', ...)` were both errors while
    their opposites worked.

 ** The distribution objects:
    `prob.KernelDistribution` hides `NumParameters`, `ParameterNames` and
    `ParameterDescription`, MATLAB carrying none of the three, and
    `prob.StableDistribution` no longer lists `ParameterCI`; all remain
    readable by name.  The classes list `Truncation` and `IsTruncated` where
    MATLAB lists them.  `MultinomialDistribution.random` and
    `LoguniformDistribution.random` were broken in every call form, and
    `KernelDistribution`'s `pdf`, `cdf` and `icdf` errored on an empty query.

 ** The learner classes:
    each reaches the property and method surface MATLAB gives it.
    `Intercept`, `CategoricalPredictors`, `ExpandedPredictorNames`, `W`,
    `BetweenSigma`, `KernelParameters`, `BoxConstraints`, `OutlierFraction`,
    `Nu` and `BinEdges` are added where each was missing, and the ten classes
    with a MATLAB counterpart declare `HyperparameterOptimizationResults`,
    read-only and always empty.  Every classification learner accepts a
    response given as a character matrix, which the documentation always
    listed and which had never worked.  Every classifier with a settable
    `Cost` validates the matrix as MATLAB does and accepts a struct of
    `ClassNames` and `ClassificationCosts`; `Prior` accepts the matching
    struct form.  The seventeen supervised classes enforce access with
    property attributes rather than hand-written `subsref` and `subsasgn`
    whitelists.  Setting `ScoreTransform` to 'none' or 'identity' made
    `predict` raise on four classes, and assigning it raised on five others,
    so the property could not be set at all.  'ismax' and 'symmetricismax'
    mark the largest score of each observation, where the maximum was taken
    down the column.

 ** The paired argument parser:
    `crossval`, `grpstats`, `rmmissing`, `stepwisefit` and `scatterhist`
    parse Name-Value arguments through `parsePairedArguments` from the
    `datatypes` package, and the statistics package's own private
    `pairedArgs` is gone.

 ** tiedrank:
    accepts MATLAB's fourth argument, a tolerance, which defaults to exact
    comparison so every existing call is unaffected.

 ** violin:
    a row vector is read as one variable, a cell of row vectors works,
    integer and logical observations are accepted, and a single observation,
    an empty input and a call with no arguments report what is wrong instead
    of failing inside the function.

 ** wblplot:
    a non-finite observation is rejected; `wblplot ([1, Inf, 2, 3])` never
    returned, creating nine graphics objects per iteration for as long as it
    was left alone.

 Removed functions:
 ==================

 ** mvtcdfqmc:
    the quasi-Monte-Carlo integrator behind `mvtcdf` and `mvncdf` is now the
    private helper `__mvtcdfqmc__` and can no longer be called directly.
    MATLAB ships no such function, so nothing portable depended on it.  Call
    `mvtcdf` or `mvncdf` instead.

 Summary of important user-visible changes for statistics 1.9.1:
-------------------------------------------------------------------

 Improvements:
 =============

 ** ClassificationKNN:
    a custom distance function handle works again.  The constructor probed
    the handle against the response instead of the predictors and sized the
    result against the number of response rows, so a correctly written
    `distfun` was rejected and no custom metric could be used at all.  A
    handle assigned to `Distance` after fitting was accepted without being
    probed and failed later inside `predict`, and `disp` could not print
    one.  The `D2 = distfun (ZI, ZJ)` signature is now documented in the
    property's help text.

 ** documentation:
    `doc/statistics.qch` is rebuilt with pkg-octave-doc 0.7.7.  Double-
    clicking the package in the GUI Documentation tab opens an overview
    listing every documented name under its category, rather than whichever
    category came first, and the one formula that reached the page as raw
    TeX now renders as the plain text form of its docstring.  The online
    pages for `NonLinearModel` and `gmdistribution` were published as plain
    function pages, listing none of their properties or methods, because a
    member documented outside texinfo made the class renderer fail and fall
    back silently; both are rendered as classes again, restoring 105 and 72
    documented members.
