Query SGELQF workspace in SGELSS, as D/C/ZGELSS do - #1428
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Path 2a computed the SGELQF workspace as M*ILAENV(1,'SGELQF',...), which duplicates SGELQF's own formula. Use a workspace query instead, as DGELSS, CGELSS and ZGELSS do. The returned LWORK is unchanged.
langou
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Sep 26, 2026
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This is great. Thanks @kyungminlee
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #1428 +/- ##
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- Coverage 69.36% 69.33% -0.03%
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Files 6122 6122
Lines 486717 487029 +312
Branches 23268 23268
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- Misses 148689 148903 +214
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SGELSS still computes the SGELQF term of its Path 2a workspace as M*ILAENV(1, 'SGELQF', ...), which repeats the formula inside the reference SGELQF instead of asking SGELQF. Commit 9e96fbe (bug 0065, LAPACK 3.4.0) replaced the ILAENV workspace formulas in DGELSS, CGELSS and ZGELSS with workspace queries, and they have asked ?GELQF since then. In SGELSS it converted the SGEBRD, SORMBR, SORGBR and SORMLQ terms but left this one, the only workspace formula still in the file:
lapack/SRC/sgelss.f
Lines 323 to 324 in 9e518f1
With the reference SGELQF the formula and the query agree, because the query returns M*NB from the same ILAENV call whenever MIN(M, N) > 0, and Path 2a is only taken then. So the LWORK that SGELSS returns does not change. Workspace queries at a few Path 2a sizes return the same LWORK before and after the change.
Replace the formula with a workspace query, as 9e96fbe did in dgelss.f, so that SGELSS no longer depends on how SGELQF sizes its workspace.