    DIST-QUANTITIES:  Quantities defined for a specified distribution.

    The plot and histogram programs used with the 'dist' programs,
    dist-plt and dist-hist, have the generic facilities documented in
    xxx-plt.doc and xxx-hist.doc.  In addition to the generic quantities
    (see quantities.doc) and the Markov chain quantities (see
    mc-quantities.doc), these programs can also reference the state
    variables for the specified distribution, under the names used in
    dist-spec.  Furthermore, if the distribution is a Bayesian posterior,
    the following quantities are defined:

        P    Log of the prior probability of the parameters.

        l    Array of minus log probabilities for training cases,
             obtained from the likelihood formula.  If not specified
             to be an array, the average minus log probability over
             training cases.

        in   Array of containing the n'th input for the training cases.

        tn   Array of containing the n'th target for the training cases.

    Note that n is required for in and tn above - without it, they mean
    entirely different things (see quantities.doc and mc-quantities.doc).
    Note that, for historical reasons, 'P' is the log probability, but
    'l' is minus the log probability.

    For example, if the distribution was specified by

        > dist-spec log "x1^2 + x2^2 + w^2"

    then after dist-mc was run, the quantities x1, x2 and w could be
    plotted using a command such as

        > dist-plt t x1x2w log | plot

    If the distribution is a Bayesian posterior, the command

        > dist-plt t t2@0:9 log | plot

    will plot target number 2 (numbered starting at 0) for the first ten
    observations.

                Copyright (c) 1995-2003 by Radford M. Neal