QR and permutation matrix

10262015, 03:04 PM
(This post was last modified: 10262015 03:18 PM by Han.)
Post: #1




QR and permutation matrix
The QR() command returns the QR factorization of a matrix and includes a permutation matrix. I cannot seem to find an example of a matrix for which the QR factorization returns a permutation matrix that is nonidentity. Is anyone able to find such a case? From the looks of it, the QR() command does not appear to do any pivoting (the diagonals of R are not in nonincreasing order). For example:
M2:=[[1,2],[3,5],[1,7],[2,1]] QR(M2); returns Code: [ So is there no pivoting? And if not, then it appears the P matrix is superfluous. Graph 3D  QPI  SolveSys 

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Messages In This Thread 
QR and permutation matrix  Han  10262015 03:04 PM
RE: QR and permutation matrix  parisse  10262015, 05:04 PM
RE: QR and permutation matrix  Han  10262015, 07:24 PM
RE: QR and permutation matrix  Han  10262015, 05:16 PM
RE: QR and permutation matrix  parisse  10272015, 06:48 AM

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