Re: [Help-glpk] Two capabilities questions

[Erik de Castro Lopo]

Andrew,

Thanks very much for your reply and your good work on this library. If
you ever require a library for reading or writing sound files I hpoe you
would choose my library ( http://www.zip.com.au/~erikd/libsndfile/ ).

On Thu, 20 Dec 2001 17:19:13 +0300
"Andrew Makhorin" <address@hidden> wrote:

> >1) Can GLPK solve problems where the solution vector has bounded but
> >   negative coefficients? The problem I am interested in solving has
> >   coefficients in the range [-1.0, 1.0]. (I am aware that I can fiddle
> >   the problem to require coefficients >= 0 but this further complicates
> >   matters).
> 
> If you mean bounds of structural variables, 

I read the guide again. I was not asking about the structural variables
but the coefficients of the objective function (ie the c_sub_n in equation
1.1 of the guide). 

Traditional LP assumes that these are all non-negative but they don't have to 
be and the guide does not explicitly state that this is a requirement. 

For the moment I will assume that bounded negative values are allowed are start
playing with this library.

<snip>

> You can use API routines glp_simplex1() and glp_simplex2(), which allow
> you to solve LP using an initial basis explicitly specified in LPI. For
> details see the text file 'newapi.txt' included in the package.

Wonderful! That is just what I need.

Regards,
Erik
-- 
+-----------------------------------------------------------+
  Erik de Castro Lopo  address@hidden (Yes it's valid)
+-----------------------------------------------------------+
Orcad Express 9: "Its a nice demo but I wouldn't want to use it 
on a day-to-day basis" -- me