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## Re: Using the downsimplex routine

 From: Ben Sapp Subject: Re: Using the downsimplex routine Date: Thu, 16 Mar 2000 09:28:20 -0700

```Hi Mike,

I have been working on a program to do just this thing.   At one point I
had it so that it could solve your problem.  At that point it could have
both equalities and inequalities in the constraint equation.  I wanted
to make it even more general and in the process I have broken it.  I
broke it when I tried to make the 'with' line below look like this

with u(i)>x(i)>l(i), for i=1,2,3.   u and l are vectors that represent
the upper and lower bounds respectively.

At any rate I am not working on it very much.  So, it could be a while
before I get it corrected.  If you would like it you are certainly
welcome to have a look at it.  One more drawback of it is that it is in
C++ and so it needs to be dynamically linked with Octave.(This might
also be a blessing)  I have run it only on the bleeding-edge versions of
Octave.   If you want to do some debugging let me know and I will post
it on the web.

MIKE DESILETS wrote:
>
> I have tested Etienne Grossmann's 'downsimplex' routine and it was
> successful in computing the example functions from the code
> documentation, however, the documentation is not clear enough and I am
> inexperienced enough in linear programming to understand how I could use
> this routine to solve the following problem:
> maximize(or minimize)  z = 3x(1) + 2x(2) +x(3)
> subject to                    2x(1) + x(2) + x(3) <= 150
> with x(1)>=0,x(2)>=0,x(3)>=0
>
> I understand that Octave has been integrating more optimisation tools so
> I never expected the optimisation process to be a simple one, however I
> do need to know if this routine has the ability to adress this type of
> linear programming problem and what steps I might take to find further
> documentation on its use.
>
> Thanks for taking the time to read,
>
> michael

--
Ben Sapp                         Los Alamos National Laboratory
Fax:   (505)665-7920             URL:   http://www.neutrino.lanl.gov/
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