[MATH-1176] QRDecomposition does not detect the matrix singularity

• Type: Bug
• Status: Reopened
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 3.3
• Fix Version/s: 4.X
• Assignee: Unassigned
• Reporter: alberto trivellato
• Created: 04/Dec/14 11:20
• Updated: 05/Jun/21 13:07

Description

QRDecomposition fails this test. The default contructor sets the threshold=0, so we will never have abs(Rii) <= 0

public void testSimpleRankDeficient() throws Exception {
double[][] A = new double[][] {

{ 1, 2, 3 }

,

{ 4, 5, 6 }

,
{ 7, 8, 9 }};
//this matrix is singular

RealMatrix M2 = MatrixUtils.createRealMatrix(A);
QRDecomposition qr2 = new QRDecomposition(M2);
assertFalse(qr2.getSolver().isNonSingular());//this fails
}

Issue Links

• is related to: MATH-1024 LU and QR have different default singularity thresholds