Help for SORT

PURPOSE

	SORT performs a multiple column sort on an IBIS interface file. The
program starts with the column defined as primary and performs an incore sort.
Subsequent columns are sorted only within limits established by equal values
in previously sorted columns. The program incorporates two temporary fields as
sorting and indexing columns. The index column can be retained for later use
if specified.

TAE COMMAND LINE FORMAT

	sort INP=A SORTCOL=(B,C,D,E,...F) INDEXCOL=G
	sort INP=A SORTCOL=(B,C,D,E,...F) DESCEND INDEXCOL=G

	INP is a random access file which is read from or written to depending
on the parameters. SORTCOL specifies the columns to be sorted in the order in
which the sort is to occur. DESCEND is a keyword whose presence indicates that
all the columns are to be sorted in descending order. INDEXCOL is an integer
which designates the column to recieve the index numbers assigned to each
unique combination of letters or numbers in the sorted columns created by the
sorting process. The columns can be numdric or alphabetic, or a mixture of
the two in the case of multiple column sorts.

EXAMPLE

	sort INP=A SORTCOL=(1,2) INDEXCOL=3

	In this example an 8 character name is stored in the first 2 columns.
The file is sorted into alphabetic order. The index stored in column 3 can be
used in place of the names for other operations such as aggregation.

OPERATION

	SORT uses two temporary arrays. The first holds the SORT data and the
second defines the boundary limits. Limits are defined using an index number
which indicates the portion of the file to be sorted. The boundary index is
initialized to 1 which indicates that the entire column is to be sorted. As
subsequent sorts are made on the file the index number is broken into groupings
of the same number which indicate the sort limits. The holding array is sorted
each time the index changes to achieve a multiple column sort.

	At the completion of the sort process, the reordering is in the form
of pointers. The pointers are used to move all the columns of the file one at
a time. The limit array serves as an index.

WRITTEN BY		A. L. Zobrist		15 Dec 1976
COGNIZANT PROGRAMMER	K. F. Evans
DOCUMENTED BY		R. Wayne Bannister
REVISION HISTORY
  1995-03-06 C. Randy Schenk (CRI) - Ported to UNIX
  2000-09-04 A. Zobrist - rewritten in C
  2008-01-02 WLB - switched to USES_ANSI_C AND LIB_CARTO; misc cleanup  

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