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https://issues.apache.org/jira/browse/MATH-290?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12747692#action_12747692
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Benjamin McCann edited comment on MATH-290 at 8/26/09 8:51 AM:
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The original patch is sufficient, but I'm attaching a new one that also cleans
up some code formatting (weird spacing in SimplexTableau) and also provides a
little bit better test.
Andrea, the correct solution for the example you provided is 0. You restricted
the variables to be non-negative and are trying to minimize the objective
function, so the best you can do is make both variables 0 for an objective
function value of 0.
was (Author: bmccann):
My earlier comments were misleading. I misread the example provided (I
need more sleep!). The original patch is sufficient. I'm attaching a new one
that also cleans up some code formatting (weird spacing in SimplexTableau) and
also provides a little bit better test.
Andrea, the correct solution for the example you provided is 0. You restricted
the variables to be non-negative and are trying to minimize the objective
function, so the best you can do is make both variables 0 for an objective
function value of 0.
> 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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