GLPK and GLPK for java - Installation tutorial and Eclipse configuration

glpk-java.as

#
# author Huber Flores
#

GLPK Tutorial

Requires Eclipse 3.7 (Indigo). At the moment, there is no official plugin for Juno

#Install dependecies
> sudo 
> apt-get install build-essential glpk openjdk-7-jdk libtool swig   (Synaptic Package Manager includes all the dependencies automatically)

#set java home
> export $JAVA_HOME=/usr/lib/jvm/jdk1.7.0_40/bin/java
#check
> echo $JAVA_HOME
/usr/lib/jvm/jdk1.7.0_40/bin/java

#GLPK installation
$ wget ftp://ftp.gnu.org/gnu/glpk/glpk-4.55.tar.gz
$ tar -xzf glpk-4.55.tar.gz
$ cd glpk-4.55

$./configure
$ make
$ make check
$ sudo make install
$ sudo ldconfig

$ glpsol --version
GLPSOL: GLPK LP/MIP Solver, v4.55

Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
2009, 2010, 2011, 2013, 2014 Andrew Makhorin, Department for Applied
Informatics, Moscow Aviation Institute, Moscow, Russia. All rights
reserved. E-mail: <mao@gnu.org>.

This program has ABSOLUTELY NO WARRANTY.

This program is free software; you may re-distribute it under the terms
of the GNU General Public License version 3 or later.


#GLPK for Java
#This will create the jar files to include in the project and an interface with GLPK installed in the OS

> tar -xzf glpk-java-1.0.37.tar.gz
> cd glpk-java-1.0.37

>./configure

>./configure \
CPPFLAGS=-I/System/Library/Frameworks/JavaVM.framework/Headers \
SWIGFLAGS=-I/System/Library/Frameworks/JavaVM.framework/Headers

Assuming libglpk.so is in different location, then

$ ./configure LDFLAGS=-L/usr/share/lib/jni

$ make
$ make check
$ sudo make install
$ sudo ldconfig

#Jars generated: glpk-java-1.0.37.jar, glpk-java-1.0.37-sources.jar, glpk-java-1.0.37-javadocs.jar
#Include glpk-java-1.0.37.jar in the classpath of your project
#Also add in Ecliṕse a reference to the folder /swig/.libs as link for java.library.path (screenshot:https://raw.githubusercontent.com/huberflores/GenericCode/master/LinearProgramming/optimj-Djava.library.path-link.png)


#FAQ
1. Be careful with installing the right version of GLPK and GLPK for java. If there is a mismatch between versions, then it will be hard to install it. 

Potential error if there is a version mismatch
make[2]: *** [all] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2



#Example
1. Open Eclipse and create a new "Java Project"
2. Create a class "Example1"
3. Paste the code below (This example comes with the GLPK framework and is located in the folder examples)

package ee.cs.ut.example1;

import org.gnu.glpk.GLPK;
import org.gnu.glpk.GLPKConstants;
import org.gnu.glpk.GlpkException;
import org.gnu.glpk.SWIGTYPE_p_double;
import org.gnu.glpk.SWIGTYPE_p_int;
import org.gnu.glpk.glp_prob;
import org.gnu.glpk.glp_smcp;

public class Example1 {
    //	Minimize z = -.5 * x1 + .5 * x2 - x3 + 1
    //
    //	subject to
    //	0.0 <= x1 - .5 * x2 <= 0.2
    //  -x2 + x3 <= 0.4
    //	where,
    //	0.0 <= x1 <= 0.5
    //	0.0 <= x2 <= 0.5
    //  0.0 <= x3 <= 0.5

    public static void main(String[] arg) {
        glp_prob lp;
        glp_smcp parm;
        SWIGTYPE_p_int ind;
        SWIGTYPE_p_double val;
        int ret;

        try {
            // Create problem
            lp = GLPK.glp_create_prob();
            System.out.println("Problem created");
            GLPK.glp_set_prob_name(lp, "myProblem");

            // Define columns
            GLPK.glp_add_cols(lp, 3);
            GLPK.glp_set_col_name(lp, 1, "x1");
            GLPK.glp_set_col_kind(lp, 1, GLPKConstants.GLP_CV);
            GLPK.glp_set_col_bnds(lp, 1, GLPKConstants.GLP_DB, 0, .5);
            GLPK.glp_set_col_name(lp, 2, "x2");
            GLPK.glp_set_col_kind(lp, 2, GLPKConstants.GLP_CV);
            GLPK.glp_set_col_bnds(lp, 2, GLPKConstants.GLP_DB, 0, .5);
            GLPK.glp_set_col_name(lp, 3, "x3");
            GLPK.glp_set_col_kind(lp, 3, GLPKConstants.GLP_CV);
            GLPK.glp_set_col_bnds(lp, 3, GLPKConstants.GLP_DB, 0, .5);

            // Create constraints

            // Allocate memory
            ind = GLPK.new_intArray(3);
            val = GLPK.new_doubleArray(3);

            // Create rows
            GLPK.glp_add_rows(lp, 2);

            // Set row details
            GLPK.glp_set_row_name(lp, 1, "c1");
            GLPK.glp_set_row_bnds(lp, 1, GLPKConstants.GLP_DB, 0, 0.2);
            GLPK.intArray_setitem(ind, 1, 1);
            GLPK.intArray_setitem(ind, 2, 2);
            GLPK.doubleArray_setitem(val, 1, 1.);
            GLPK.doubleArray_setitem(val, 2, -.5);
            GLPK.glp_set_mat_row(lp, 1, 2, ind, val);

            GLPK.glp_set_row_name(lp, 2, "c2");
            GLPK.glp_set_row_bnds(lp, 2, GLPKConstants.GLP_UP, 0, 0.4);
            GLPK.intArray_setitem(ind, 1, 2);
            GLPK.intArray_setitem(ind, 2, 3);
            GLPK.doubleArray_setitem(val, 1, -1.);
            GLPK.doubleArray_setitem(val, 2, 1.);
            GLPK.glp_set_mat_row(lp, 2, 2, ind, val);

            // Free memory
            GLPK.delete_intArray(ind);
            GLPK.delete_doubleArray(val);

            // Define objective
            GLPK.glp_set_obj_name(lp, "z");
            GLPK.glp_set_obj_dir(lp, GLPKConstants.GLP_MIN);
            GLPK.glp_set_obj_coef(lp, 0, 1.);
            GLPK.glp_set_obj_coef(lp, 1, -.5);
            GLPK.glp_set_obj_coef(lp, 2, .5);
            GLPK.glp_set_obj_coef(lp, 3, -1);

            // Write model to file
            // GLPK.glp_write_lp(lp, null, "lp.lp");

            // Solve model
            parm = new glp_smcp();
            GLPK.glp_init_smcp(parm);
            ret = GLPK.glp_simplex(lp, parm);

            // Retrieve solution
            if (ret == 0) {
                write_lp_solution(lp);
            } else {
                System.out.println("The problem could not be solved");
            }

            // Free memory
            GLPK.glp_delete_prob(lp);
        } catch (GlpkException ex) {
            ex.printStackTrace();
        }
    }

    /**
     * write simplex solution
     * @param lp problem
     */
    static void write_lp_solution(glp_prob lp) {
        int i;
        int n;
        String name;
        double val;

        name = GLPK.glp_get_obj_name(lp);
        val = GLPK.glp_get_obj_val(lp);
        System.out.print(name);
        System.out.print(" = ");
        System.out.println(val);
        n = GLPK.glp_get_num_cols(lp);
        for (i = 1; i <= n; i++) {
            name = GLPK.glp_get_col_name(lp, i);
            val = GLPK.glp_get_col_prim(lp, i);
            System.out.print(name);
            System.out.print(" = ");
            System.out.println(val);
        }
    }
}


4. Right click in the project -> Run as java application
5. Output

Problem created
GLPK Simplex Optimizer, v4.55
2 rows, 3 columns, 4 non-zeros
*     0: obj =   1.000000000e+00  infeas =  0.000e+00 (0)
*     3: obj =   4.250000000e-01  infeas =  0.000e+00 (0)
OPTIMAL LP SOLUTION FOUND
z = 0.42500000000000004
x1 = 0.25
x2 = 0.09999999999999998
x3 = 0.5

6. Project can be fork from here https://github.com/huberflores/GenericCode/tree/master/LinearProgramming


References:
- https://en.wikibooks.org/wiki/GLPK/Java