Copyright (c) 1991-94 The Board of Trustees of the University of Illinois

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INPUT FORMAT

The raw data for the 3D alpha shape software are 3D points, each given
by its 3 coordinates.  Each point set is given in an ASCII data file
with the following simple format:

        #title: <TITLE>         title line (optional),
        #scale: <SCALE>         scale command (optional),
        #fix: <W>.<A>           fixed-point command (optional),
        # blah blah blah        comment line (ignored),
        <blank line>            blank line (also ignored),
        <X> <Y> <Z>             data line containing three coordinates.

The i-th data line of the input file holds the coordinates of point i.
It should be noted that the programs refers to a specific point by its
index.  Also note that the i-th data line is not necessarily the i-th
line of the input file.

By default, we require the coordinates to be integers; other types are to
be converted to integers with absolute values less than 2^31 = 2147483648.
It is, however, possible to specify coordinates in fixed-point format, using
the fixed-point command.  For example, the line

        #fix: 7.5

at the beginning of the data file, tells the program to expect coordinates
with up to 7 significant decimal digits, of which up to 5 are after the
decimal point.  So, coordinates like 55, -1234567, -5.5, 12.34567, or 0.00007 
are acceptable, but, for example, 7e-7 is not.

For additional convenience, the scale command multiplies all coordinates
uniformly.  For example,

        #scale: 1e-3

divides the given coordinates by 1000 each.

IMPLEMENTATION NOTE: Internally, the code works with long-integer numbers.
The reason for this is the implicit use of a symbolic perturbation method
to resolve degenerate cases (see Edelsbrunner and Mucke [1]).  The scale
command is therefore relevant only to application programs with graphics
or output of metric information.  The fixed-point command also does internal
scaling.  Its main purpose is to enhance user-friendliness by allowing
fixed-point real input.

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FORMAT CONVERSION UTILITIES

A utility function pdb2alpha is provided to convert standard protein
data bank (pdb) files to our input format.  Execute

        % pdb2alpha <INFILE> <OUTFILE>

where <INFILE> denotes the path of the file in pdb format and <OUTFILE>
is the path of the converted file in alpha shape input format.

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AUTOMATIC DECOMPRESSION

If the code is compiled with the "automatic decompression" feature
turned on,  it will recognize compressed data files based on their
file extension -- *.Z for compress, *.z or *.gz for gzip -- and if
so, it will decompress the data on the fly.  This feature can be used
to save disk space.  For example, you can have a cronjob running a
script that routinely keeps your data files compressed; for example:

        % find $HOME -name \*.alf -exec compress '{}' ';'
        % find $HOME -name \*.dt  -exec compress '{}' ';'

would compress all the intermediate data files in your home directory
tree.  Keep in mind that ASCII files usually compress by more than
60%, whereas the binary *.dt and *.alf files compress only by 25-35%
and 35-50%, respectively.  Cf: man compress; man gzip; man crontab.
Also: GNU's gzip usually compresses far better than the standard
compress utility.

Note: If you wish, you can also keep the input files (the ones with
the point coordinates) compressed; but, eg, keeping the *.info files
compressed won't necessarily work.

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QUOTE
            ..................................................................
            "EOF or format error while reading vertex 1 (out of 101) at line 1.
            IOT trap (core dumped)"
            --Detri error message while reading an invalid input file
            ...................................................................