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[Lapack] [Fwd: LAPACK Error Report (fwd)] (fwd)

Hello guys,

bug report on pzlahqr, if somebody has time to investigate let 
me know.

Thanks for the bug report Nakahara,
yes obviously
if the routine p[c-z]lahqr uses its do-loop 20, element S1(1,0) and 
S1(0,1) are accessed, that's pretty clear:

522             DO 20 II = 2*JBLK, 1, -1
523                S1( II, II ) = CONST*( CABS1( S1( II, II ) )+
524      $                        CABS1( S1( II, II-1 ) ) )
525                S1( II, II-1 ) = ZERO
526                S1( II-1, II ) = ZERO
527    20       CONTINUE

Unfortunately the ScaLAPACK testing are not exercizing this part of the 
code, it is done only when:

518          IF( ( ITS.EQ.20 .OR. ITS.EQ.40 ) .AND. ( JBLK.GT.1 ) ) THEN

The maximum number of ITS necessary in the testing is 6. So no easy way to 
test a solution right now. I think the solution is simply to avoid the 
reference to S(1,0) and S(0,1) when it occurs but can not confirm it.


---------- Forwarded message ----------
Date: Mon, 13 Mar 2006 20:41:47 -0500 (EST)
From: Yasuhiro Nakahara 
Subject: LAPACK Error Report

LAPACK Error Report Submission.

Package:     ScaLAPACK
Type:        routine-source
Description: pzlahqr routine was aborted due to a segmentation fault.
I found an invalid memory access at the line 525 in pzlahqr.f.
In the DO-loop, with II=1, S1(1, 0) was accessed.


    Machine Information

System:          Celeron 2.40GHz; 256MB RAM
OS:              Windows 2000, Cygwin
Compiler:        GNU gcc v.3.3.3
Compiler flags:  -funroll-all-loops -O2 -g
BLAS:            ATLAS v3.7.11
Atlas options:   -fomit-frame-pointer -O3 -funroll-all-loops

     Personal Information

First name:  Yasuhiro
Last name:   Nakahara
Email:       ***@***
Company:     Canon inc.
Experience:  expert

Mon Mar 13 20:41:47 2006

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