When BWL=BWU=0, LDBB evaluates to 0.
Later when it is passed to dgetrf, it triggers an error as the lead is expect to be positive.
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CALL DGETRF( N-LN, N-LN, AF( BBPTR+BW*LDBB ), LDBB, |
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$ IPIV( LN+1 ), INFO ) |
** On entry to DGETRF parameter number 4 had an illegal value
pdgbtrs will further raise a few errors when BWL=BWU=0.
Here is a MWE.
program gbsv_test
implicit none
integer ictxt
integer n, kl, ku, ja, laf, lwork, info
integer, dimension(10) :: desca, ipiv, af, work
double precision a
call blacs_get(-1, 0, ictxt)
call blacs_gridinit(ictxt, 'R', 1, 1)
n = 1
kl = 0
ku = 0
a = 1.0
ja = 1
laf = 10
lwork = 10
info = 0
desca(1) = 501
desca(2) = ictxt
desca(3) = 1
desca(4) = 1
desca(5) = 0
desca(6) = 1
call pdgbtrf(n, kl, ku, a, ja, desca, ipiv, af, laf, work, lwork, info)
call blacs_gridexit(ictxt)
call blacs_exit(0)
end program gbsv_test
When
BWL=BWU=0,LDBBevaluates to0.scalapack/SRC/pdgbtrf.f
Line 829 in a23c2cd
Later when it is passed to
dgetrf, it triggers an error as the lead is expect to be positive.scalapack/SRC/pdgbtrf.f
Lines 860 to 861 in a23c2cd
pdgbtrswill further raise a few errors whenBWL=BWU=0.Here is a MWE.