Hello Scalapack,
I have been using the pivoted QR factorisation routine (pzgeqpf) from
scalapack-1.8.0. I have found that, in some cases, the diagonal
elements of the R matrix are not arranged in order of descending
magnitude as described in the user's guide. I have attached a test
case for you to verify. e.g. I get something like:
R(0,0) -0.707107 + 0i
R(1,1) -0.707107 + 0i
R(2,2) 8.16273e-17 + 0i
R(3,3) -0.243173 + 0i
R(4,4) 4.82605e-17 + 0i
This behaviour can be reproduced for the single precision complex case
(although not with the supplied test matrix). The same test case
works for the real case (pdgeqpf). e.g.
R(0,0) -0.707107
R(1,1) -0.707107
R(2,2) 0.5
R(3,3) 3.96991e-17
R(4,4) 2.2336e-17
I have not had any problems with the equivalent lapack routines (zgeqp3),
and have not see any mention of this in the errata.
David
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pzgeqpf_test.c
Type: text/x-csrc
Size: 4914 bytes
Desc: not available
Url :
http://lists.eecs.utk.edu/mailman/private/scalapack/attachments/20111019/1ec05dac/pzgeqpf_test.bin
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pdgeqpf_test.c
Type: text/x-csrc
Size: 4460 bytes
Desc: not available
Url :
http://lists.eecs.utk.edu/mailman/private/scalapack/attachments/20111019/1ec05dac/pdgeqpf_test.bin
|