LAPACK 3.12.0
LAPACK: Linear Algebra PACKage
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◆ dlaqz4()

subroutine dlaqz4 ( logical, intent(in) ilschur,
logical, intent(in) ilq,
logical, intent(in) ilz,
integer, intent(in) n,
integer, intent(in) ilo,
integer, intent(in) ihi,
integer, intent(in) nshifts,
integer, intent(in) nblock_desired,
double precision, dimension( * ), intent(inout) sr,
double precision, dimension( * ), intent(inout) si,
double precision, dimension( * ), intent(inout) ss,
double precision, dimension( lda, * ), intent(inout) a,
integer, intent(in) lda,
double precision, dimension( ldb, * ), intent(inout) b,
integer, intent(in) ldb,
double precision, dimension( ldq, * ), intent(inout) q,
integer, intent(in) ldq,
double precision, dimension( ldz, * ), intent(inout) z,
integer, intent(in) ldz,
double precision, dimension( ldqc, * ), intent(inout) qc,
integer, intent(in) ldqc,
double precision, dimension( ldzc, * ), intent(inout) zc,
integer, intent(in) ldzc,
double precision, dimension( * ), intent(inout) work,
integer, intent(in) lwork,
integer, intent(out) info )

DLAQZ4

Download DLAQZ4 + dependencies [TGZ] [ZIP] [TXT]

Purpose:
!>
!> DLAQZ4 Executes a single multishift QZ sweep
!>
Parameters
[in]ILSCHUR
!>          ILSCHUR is LOGICAL
!>              Determines whether or not to update the full Schur form
!>
[in]ILQ
!>          ILQ is LOGICAL
!>              Determines whether or not to update the matrix Q
!>
[in]ILZ
!>          ILZ is LOGICAL
!>              Determines whether or not to update the matrix Z
!>
[in]N
!>          N is INTEGER
!>          The order of the matrices A, B, Q, and Z.  N >= 0.
!>
[in]ILO
!>          ILO is INTEGER
!>
[in]IHI
!>          IHI is INTEGER
!>
[in]NSHIFTS
!>          NSHIFTS is INTEGER
!>          The desired number of shifts to use
!>
[in]NBLOCK_DESIRED
!>          NBLOCK_DESIRED is INTEGER
!>          The desired size of the computational windows
!>
[in]SR
!>          SR is DOUBLE PRECISION array. SR contains
!>          the real parts of the shifts to use.
!>
[in]SI
!>          SI is DOUBLE PRECISION array. SI contains
!>          the imaginary parts of the shifts to use.
!>
[in]SS
!>          SS is DOUBLE PRECISION array. SS contains
!>          the scale of the shifts to use.
!>
[in,out]A
!>          A is DOUBLE PRECISION array, dimension (LDA, N)
!>
[in]LDA
!>          LDA is INTEGER
!>          The leading dimension of the array A.  LDA >= max( 1, N ).
!>
[in,out]B
!>          B is DOUBLE PRECISION array, dimension (LDB, N)
!>
[in]LDB
!>          LDB is INTEGER
!>          The leading dimension of the array B.  LDB >= max( 1, N ).
!>
[in,out]Q
!>          Q is DOUBLE PRECISION array, dimension (LDQ, N)
!>
[in]LDQ
!>          LDQ is INTEGER
!>
[in,out]Z
!>          Z is DOUBLE PRECISION array, dimension (LDZ, N)
!>
[in]LDZ
!>          LDZ is INTEGER
!>
[in,out]QC
!>          QC is DOUBLE PRECISION array, dimension (LDQC, NBLOCK_DESIRED)
!>
[in]LDQC
!>          LDQC is INTEGER
!>
[in,out]ZC
!>          ZC is DOUBLE PRECISION array, dimension (LDZC, NBLOCK_DESIRED)
!>
[in]LDZC
!>          LDZ is INTEGER
!>
[out]WORK
!>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
!>          On exit, if INFO >= 0, WORK(1) returns the optimal LWORK.
!>
[in]LWORK
!>          LWORK is INTEGER
!>          The dimension of the array WORK.  LWORK >= max(1,N).
!>
!>          If LWORK = -1, then a workspace query is assumed; the routine
!>          only calculates the optimal size of the WORK array, returns
!>          this value as the first entry of the WORK array, and no error
!>          message related to LWORK is issued by XERBLA.
!>
[out]INFO
!>          INFO is INTEGER
!>          = 0: successful exit
!>          < 0: if INFO = -i, the i-th argument had an illegal value
!>
Author
Thijs Steel, KU Leuven
Date
May 2020