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[Help-glpk] [Fwd: Re: Building a graph on the fly]

From: Andrew Makhorin
Subject: [Help-glpk] [Fwd: Re: Building a graph on the fly]
Date: Tue, 17 Apr 2012 18:18:20 +0400

-------- Forwarded Message --------
From: Sylvain Fournier <address@hidden>
To: Andrew Makhorin <address@hidden>
Subject: Re: [Help-glpk] Building a graph on the fly
Date: Tue, 17 Apr 2012 10:12:27 -0300

Hi Andrew,

Thanks for your quick answer. In fact, I am looking for an example in
Java, as I can't find how to create a C struct using the Java routines,
and how to use the offsetof macro.
Does the '_' prefix for the class names _glp_graph, _glp_arc and
_glp_vertex (in Java) mean something special? (I guess they are
supported, as they can be found in the glpk-java.pdf documentation)
Best regards.

2012/4/16 Andrew Makhorin <address@hidden>
        > I need to solve a minimum cost flow problem in Java, and for
        this I'd
        > like to use the Out-Of-Kilter algorithm included in GLPK. I
        saw there
        > is a way to build the graph reading the information from a
        text file
        > (glp_read_graph), however I wonder whether I can do it on the
        > using some routines that modify the graph.
        > I saw I can use for example glp_create_graph,
        > glp_add_arc. On the other hand, I can't find a way to create
        or modify
        > the data associated with a vertex (demand) or an arc
        (capacity, cost).
        > I had no success in searching either into the mailing list
        > or in the files included in the GLPK distribution (examples
        > documentation). Did I miss something?
        Please see the example in Subsection 2.1.5 "Solve minimum-cost
        problem with the out-of-kilter algorithm" of the document "GLPK:
        and Network Routines" (doc/graph.pdf). You need to define your
        structs, one for each node and one for each arc of the network,
        include fields to store node supply/demand, arc capacity, etc.
        When you
        call glp_mincost_okalg, you specify with the standard offsetof
        where the input data are stored in your structs and to where the
        should store the solution components.

Sylvain Fournier
Analista de Pesquisa Operacional
48 3239-2423
WPLEX Software Ltda.
Rod SC 401 no. 8600 Corporate Park bloco 5 sala 101
88050-000 Santo Antônio de Lisboa, Florianópolis SC +55 48 3239-2400

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