From help-octave-request at bevo dot che dot wisc dot edu  Tue Nov  3 18:04:09 1998
Subject: Re: uniq function?
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Daniel Heiserer <Daniel dot Heiserer at bmw dot de>
Cc: Andrea Cavallini <acav at ing12 dot unife dot it>, help-octave@bevo.che.wisc.edu
Date: Tue, 3 Nov 1998 17:55:11 -0600 (CST)

On  3-Nov-1998, Daniel Heiserer <Daniel dot Heiserer at bmw dot de> wrote:

| Well intersection bases on create_set as far as I have seen. 
| Here a little benchmark between "create_set" and "unique".
| Unique is a factor 70 faster!!!!
| 
| octave:3> a=1:1000000;
| octave:4> b=[a,a];
| octave:5> b=sort(b);
| octave:6> tic;c=unique(b);toc
| ans = 11
| octave:7> tic;d=create_set(b);toc
| ans = 721
| octave:8> e=find(c-d)
| e = [](0x0)

The trouble is that create_set and intersection (and union, because it
calls create_set) use loops when they should probably use find or some
other method instead.  The comments in those files say that I wrote
them, but I think that is incorrect.  They were added a long time ago
and I don't remember who contributed them.  I'll see if I can figure
out who did and fix the comments.

Any volunteers for speeding them up?

Thanks,

jwe