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[Lapack] Bugs in DLASD8 and DLASD6

Dear Justin
Thank you for the bug report, and the detailed explanation
We recorded the bug on our Errata as bug 121 - 
http://www.netlib.org/lapack/Errata/index2.html#_strong_span_class_maroon_bug121_span_strong_bugs_in_dlasd8_and_dlasd6
We are going to take a look very shortly.
Sincerely,
Julie
On Sep 22, 2014, at 10:22 AM, Justin (Weiguang Si) <forswg@Domain.Removed> 
wrote:

We got a fatal error message "On entry to DLASD4 paramater number -1 had an 
illegal value" when using IpOpt. We think this is due to a bug in Lapack.

The bug is in DLASD8 (see line 276 to line 284 of DLASD8), which calls DLASD4 
and then handles the INFO =1 error return incorrectly. The error indicates 
that DLASD4 failed to converge and should have been reported as an INFO = 1 
return to DLASD8's caller. It should not have been passed to XERBLA. We also 
see similar bugs in DLASD6 (see line 414 to line 422 of DLASD6).

DLASDA shows what we think is the correct behavior (see line 486 to line 507 
of DLASDA). Here it is just passing the info value from DLASD6 back as the 
info value from DLASDA which is reasonable (setting info = 1 before returning 
might be cleaner). This method allows the higher-level subroutine that called 
DLASDA to recover from low-level convergence failure. We think that's the fix 
we need done in DLASD8 and DLASD6.

Thanks a lot for your attention.

-- 
--------------------------------------------------
Justin (Weiguang Si)

Postdoctoral Researcher
Neuromuscular Biomechanics Lab
Stanford University

forswg@Domain.Removed
weiguang@Domain.Removed
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