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https://issues.apache.org/jira/browse/MATH-290?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12747797#action_12747797
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Andrea commented on MATH-290:
-----------------------------
Hi Ben, what you say in your last comment is not true. There is no feasible
solution to my problem...
Maybe I should have expressed it in "human" readable format:
min: 1 x + 5 y;
r1: 2 x + 0 y <= -1;
x >= 0;
y >= 0;
x = 0 and y = 0 is not a valid solution since 2 * 0 + 0 * 0 (=0) is not <= -1...
The "trick" is that there will be never non-negative variables (in this case
[x, y]) that multiplied with non-negative coefficients (here [2, 0]) will
produce a negative result.
Do you agree?
> NullPointerException in SimplexTableau.initialize
> -------------------------------------------------
>
> Key: MATH-290
> URL: https://issues.apache.org/jira/browse/MATH-290
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 2.0
> Environment: Java 1.6.0_13 on Windows XP 32-bit
> Reporter: Andrea
> Attachments: SimplexSolverTest.patch, SimplexTableau.patch
>
>
> SimplexTableau throws a NullPointerException when no solution can be found
> instead of a NoFeasibleSolutionException
> Here is the code that causes the NullPointerException:
> LinearObjectiveFunction f = new LinearObjectiveFunction(new double[] { 1, 5
> }, 0 );
> Collection<LinearConstraint> constraints = new ArrayList<LinearConstraint>();
> constraints.add(new LinearConstraint(new double[] { 2, 0 }, Relationship.GEQ,
> -1.0));
> RealPointValuePair solution = new SimplexSolver().optimize(f, constraints,
> GoalType.MINIMIZE, true);
> Note: Tested both with Apache Commons Math 2.0 release and SVN trunk
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