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Created by Kutalmis Bercin@kutiMaintainer

BUG: QRMatrix: Prepended zero-valued rows lead to wrong QR decompositions

Summary

Matrices prepended with zero-valued rows lead to wrong QR decompositions. (Appended zero rows are fine). e.g.:

A = 
4 3
(
  (0 0 0)
  (1 2 3)
  (5 6 7)
  (9 10 11)
)

Reduced QR decomposition produces the following wrong R matrix:

R =
3 3
(
  (0 0 0)
  (-1 11.8322 13.3534)
  (-5 -8.88178e-16 0.828079)
)

rather than the correct R matrix:

R =
[[-1.03440804e+01 -1.17941852e+01 -1.32442899e+01]
 [ 0.00000000e+00 -9.47204446e-01 -1.89440889e+00]
 [ 0.00000000e+00  0.00000000e+00  7.10058168e-15]]
)

Steps to reproduce

Compile and execute: Test-A.zip

Environment information

    api      = 2107
    patch    = 0
    HEAD     = 72e67c7d1b
    version  = com
    compiler = Clang (system)
             = clang version 9.0.1 
    mpi      = SYSTEMOPENMPI
             = mpirun (Open MPI) 1.10.7.0.5e373bf1fd
    OS       = Description:     openSUSE Leap 15.3
    opts     = linux64ClangDPInt32Opt
Edited by Kutalmis Bercin