SORTING on the HP71
                               ===================

I have found that most sorting routines are either economical of memory and slow
or  wasteful of memory and fast.  A good while ago I found  a  filename  sorting
program  on one of the Swap Discs and have altered it in several ways to produce
a  suite of programs that all sort lists of textlines in a DATA file.  At  first
the sorting routine was  perfectly  adequate  but  as  the  files got larger the
sorting time became unacceptable.   I tried to understand how the routine worked
but I found it too complex for me.  The need for something simpler, and quicker,
prompted me to produce one of my own.  SUBSORT is what I came up with. 

Incorporation Instructions
--------------------------

1.  The subroutine assumes that R = the number  of  non-blank  lines in the DATA
file. 
2.   The  user  must  DIMension  S$[n],F$[n]  where  n  = the maximum number  of
characters on each line. 
3.  The DATA file has been READ into D$(). 
4.  Flag 0 must be available for use within this subroutine. 

Limitations
-----------

Apart  from  the obvious one of having enough memory to accomodate the 'scratch'
arrays,  I  am  not aware of there being any.  I have tested it for odd and even
length arrays, arrays in alphabetic  order  and  arrays  in  reverse  alphabetic
order, jumbled-up arrays  (the  usual  kind)  and arrays with duplicate entries.
Provision has also been made for an early exit from the sorting routine should a
fully sorted array be achieved before S>=F. 

Requests
--------

Should  any  user  be  able  to  suggest improvements to this routine that would
achieve reductions in sorting times I would welcome them. 

Mark Cracknell,
6 Stratton Mews,
Off South Street,
Leighton Buzzard,
Bedfordshire LU7 8NT,
England. 
0525-383265