twist.sh

DESCRIPTION

        twist.sh  Version 1.0
        Written by Arne Melsom
          a.melsom@dnmi.no
           (+47) 2296 3316
           August 23, 2001


>>> twist.sh compresses data from IEEE data,
>>>          with possible loss of accuracy upon decompression

>>> Syntax:
>>> twist.sh <type> <undef> <accuracy> <datafile> <nx> <ny> (<algorithm>)
>>> where
>>>   <type>      denotes the type of IEEE data on the input file:
>>>                r4 - 4 byte float numbers
>>>                i4 - 4 byte integer numbers
>>>                i2 - 2 byte integer numbers
>>>   <undef>     is a limit for undefined values
>>>                all values with absolute value exceeding the
>>>                absolute value of <undef> will be considered undefined
>>>                NOTE! Presently, twist only supports the use of
>>>                      a single undefined value
>>>   <accuracy>  is the accuracy that will be used, e.g.,
>>>                a value of 0.1 indicates that all information
>>>                beyond the first decimal will be lost
>>>                (rounded values are used)
>>>                NOTE! There is nothing to be gained by specifying
>>>                      values <1. for integer numbers
>>>   <datafile>  is the name of the file that will be compressed
>>>                (Note! The original file will not be deleted)
>>>   <nx>        is the no. of cells etc. in the first  direction
>>>   <ny>        is the no. of cells etc. in the second direction
>>>                (If 1D, set <ny> to 1)
>>>   <algorithm> is the twist algorithm that will be used, one of:
>>>                  0 - all implemented algorithms
>>>                  1 - '2+1'-algorithm
>>>                  4 - '3+2'-algorithm
>>>                  6 - '4+2'-algorithm
>>>                  9 - '4+3'-algorithm
>>>                (optional,
>>>                 if no value is specified, no. 4 will be used)