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[Lapack] Bugs in DLASD8 and DLASD6

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
<http://www.netlib.org/lapack/explore-html/d8/d96/dlasd8_8f_source.html>),
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
<http://www.netlib.org/lapack/explore-html/d6/d85/dlasd6_8f_source.html>).

DLASDA shows what we think is the correct behavior (see line 486 to line
507 of DLASDA
<http://www.netlib.org/lapack/explore-html/d4/d6f/dlasda_8f_source.html>).
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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