    XXX-PLT:  Write quantities from log files in a form suitable for plotting.

    There is a version of this program for each application (eg, net-plt).
    Each version allows the quantities defined for that application to be
    plotted.  The data for plotting is written to standard output, in a
    form appropriate for plotting.  It may be convenient to pipe this
    output into an suitable plot program (but xxx-plot does not actually
    invoke such a plot program itself).

    Usage:

       xxx-plt x-axis y-axis { log-file [ range ] } [ / { app-args } ]

    Here 'xxx' is a prefix identifying the particular incarnation of this
    program.  The 'x-axis' and 'y-axis' specifications give the quantities
    to plot on the two axes.  These are followed by specifications of
    where the data comes from.  Depending on the application, further
    arguments may follow after a slash (for which, see the documentation
    specific to that application - eg, net-plt.doc).

    For the format of the quantity specifications, see the documentation
    on quantities that are generic (quantities.doc), for Monte Carlo runs
    (mc-quantities.doc), for neural networks (net-quantities.doc), for
    Gaussian processes (gp-quantities.doc), etc.  The number of values
    specified for each axis must either be the same, or one axis must have
    only a single value (which will be reused).  For each x-axis value and
    the corresponding y-axis value, a continuous trace of data from each
    log file will be output.  Breaks will be inserted at the start of each
    log file and at the start of each new combination of values.

    Data comes from records with indexes in the specified ranges within
    the log files mentioned.  The ranges have the form "[low][:[high]]][%mod]".
    The low bound defaults to one.  If no high bound is given, the range
    extends to the highest index in the log file.  If the "%mod" option is
    present, only iterations within the range whose index is a multiple of
    "mod" are used (e.g. "5:12%3" is equivalent to 6 9 12).  If no range
    is given, the default is "1:".

    Everything is reset between log files, so it is possible that the number
    of values for a particular quantity will change from log file to log file.

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