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https://issues.apache.org/jira/browse/MATH-1094?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Bogdan Bezpartochnyy updated MATH-1094:
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Description:
Firstly I would like to point out that I'm not very proficient in linear
algebra, but in my opinion the following behavior should not occur. When I
solve the following linear system by hand it has no solution, but in commons
math it outputs x1= 7.5 x2 = 5.5
double[][] vals = {{-4.0,3.0},{5.0,6.0},{4.0,-3.0},{5.0,6.0}};
double[] vals1 = {6, 51, 33, 90};
try {
RealMatrix coefficients = new Array2DRowRealMatrix(vals, false);
DecompositionSolver solver = new
QRDecomposition(coefficients).getSolver();
RealVector constants = new ArrayRealVector(vals1, false);
RealVector slution = solver.solve(constants);
System.out.println(slution.getEntry(0) + " " + slution.getEntry(1));
}
catch (SingularMatrixException smx) {
}
was:Firstly I would like to point out that I'm not very proficient in linear
algebra, but in my opinion the following behavior should not occur.
> Incorrect linear system solution
> --------------------------------
>
> Key: MATH-1094
> URL: https://issues.apache.org/jira/browse/MATH-1094
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.2
> Environment: Oracle JDK7
> Linux x86-64
> Reporter: Bogdan Bezpartochnyy
> Labels: patch
> Attachments: Main.java
>
>
> Firstly I would like to point out that I'm not very proficient in linear
> algebra, but in my opinion the following behavior should not occur. When I
> solve the following linear system by hand it has no solution, but in commons
> math it outputs x1= 7.5 x2 = 5.5
> double[][] vals = {{-4.0,3.0},{5.0,6.0},{4.0,-3.0},{5.0,6.0}};
> double[] vals1 = {6, 51, 33, 90};
> try {
> RealMatrix coefficients = new Array2DRowRealMatrix(vals, false);
> DecompositionSolver solver = new
> QRDecomposition(coefficients).getSolver();
> RealVector constants = new ArrayRealVector(vals1, false);
> RealVector slution = solver.solve(constants);
> System.out.println(slution.getEntry(0) + " " +
> slution.getEntry(1));
> }
> catch (SingularMatrixException smx) {
> }
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