    NET-GEN:  Generate networks randomly from the prior, or with fixed values.

    Net-gen writes a series of independently-generated networks to a log
    file, with the architecture specified in that log file.

    Usage:

        net-gen log-file [ max-index ] [ "fix" [ value [ out-value ] ] ]

    The networks with indexes from zero up to the indicated index are
    generated (the default is max-index of zero).  If the log file already
    contains networks with some of these indexes, only the networks with
    indexes greater than the last one in the log file are generated.

    If just max-index is specified, the networks are generated randomly
    from the prior, using the random number seed taken from the log file
    (eg, as specified by rand-seed).

    If the "fix" option is given, the networks are not generated at
    random, but rather the parameters are set to zero and the hyperparameters
    are set to the value given.  If a special "out-value" is also given, it
    is used for weights on connections into the output units.  If no value
    is given, the hyperparameters are each set to the top-level width for that
    hyperparameter.  This option is useful for initializing iterative programs.

    No data model is required to use net-gen, but if a model is specified,
    the hyperparameters with it are generated as well.

    Two records are written for every network generated - an 'S' record
    containing the hyperparameters ('sigma' values), and a 'W' record
    containing the parameters (weights, biases, and offsets).  An 'r'
    record recording the random number generator state is written as well
    (unless "fix" was used).

                Copyright (c) 1995-2004 by Radford M. Neal