ormqr/ormlq/ormrq/ormql, unmqr/unmlq/unmrq/unmql: fix minimum workspa…#1292
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ormqr/ormlq/ormrq/ormql, unmqr/unmlq/unmrq/unmql: fix minimum workspa…#1292jschueller wants to merge 1 commit into
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…ce for tiny M,N,K
The workspace query formula LWKOPT = NW*NB + TSIZE used TSIZE = LDT*NBMAX
= 65*64 = 4160, a hardcoded constant. The blocked algorithm only stores
one T matrix block at a time (reused across loop iterations), so the
per-iteration workspace is LDT*NB, not LDT*NBMAX. For tiny M,N,K where
a single block suffices (NB >= N or NB >= K), LWKOPT was always >= 4160
regardless of problem size.
Fix: change LWKOPT = NW*NB + TSIZE -> LWKOPT = NW*NB + LDT*NB.
The NB adjustment formula when LWORK is limited must consistently use
the per-iteration T storage instead of TSIZE:
NB = (LWORK - TSIZE) / LDWORK -> NB = LWORK / (LDWORK + LDT)
Applied to all 16 routines (s,d,c,z x {orm,unm}{qr,rq,lq,ql}).
Closes Reference-LAPACK#546
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…ce for tiny M,N,K
The workspace query formula LWKOPT = NWNB + TSIZE used TSIZE = LDTNBMAX = 6564 = 4160, a hardcoded constant. The blocked algorithm only stores one T matrix block at a time (reused across loop iterations), so the per-iteration workspace is LDTNB, not LDT*NBMAX. For tiny M,N,K where a single block suffices (NB >= N or NB >= K), LWKOPT was always >= 4160 regardless of problem size.
Fix: change LWKOPT = NWNB + TSIZE -> LWKOPT = NWNB + LDT*NB.
The NB adjustment formula when LWORK is limited must consistently use the per-iteration T storage instead of TSIZE:
NB = (LWORK - TSIZE) / LDWORK -> NB = LWORK / (LDWORK + LDT)
Applied to all 16 routines (s,d,c,z x {orm,unm}{qr,rq,lq,ql}).
Closes #546