    DIST-STEPSIZES:  Display, evaluate, or set stepsizes used for dynamics.

    This program is an extension of the generic stepsizes program (see
    xxx-stepsizes.doc) for the 'dist' module.  This program includes the
    standard capability of displaying the stepsizes used by Markov chain
    sampling methods along with the "optimal" stepsizes based on second
    derivatives.  It also allows one to set the stepsizes for particular
    state variables, and to display the stepsizes used by variable name,
    rather than by numeric position in the vector of state variables.

    Usage:

        dist-stepsizes log-file index delta

    or:

        dist-stepsizes log-file { var=value }

    or:

        dist-stepsizes log-file [ index ]

    For the first form, the actual stepsizes used and the "optimal"
    stepsizes that would be selected based on the second derivatives at
    that point are displayed, the second derivatives being found by
    differences of first derivatives, using the given delta.  This is the
    same as generic stepsizes program, described in xxx-stepsizes.doc.

    The second form allows you to set the stepsizes that are used for
    particular variables.  The new stepsizes are written to the end of the
    log file, and are used in subsequent Markov chain operations until set
    to new values by a subsequent dist-stepsizes call.  Variables that are
    not mentioned have the default stepsize of one.

    The final form displays the selection of stepsizes stored at the given
    index, or the last stepsizes set if no index is given.

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