SRC/slaqz4.f(3)

NAME
SRC/slaqz4.f

SYNOPSIS

  Functions/Subroutines
subroutine slaqz4 (ilschur, ilq, ilz, n, ilo, ihi, nshifts, nblock_desired, sr, si, ss, a, lda, b, ldb, q, ldq, z, ldz, qc, ldqc, zc, ldzc, work, lwork, info)
SLAQZ4

Function/Subroutine Documentation

  subroutine slaqz4 (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, real, dimension( * ), intent(inout) sr, real, dimension( * ), intent(inout) si, real, dimension( * ), intent(inout) ss, real, dimension( lda, * ), intent(inout) a, integer, intent(in) lda, real, dimension( ldb, * ), intent(inout) b, integer, intent(in) ldb, real, dimension( ldq, * ), intent(inout) q, integer, intent(in) ldq, real, dimension( ldz, * ), intent(inout) z, integer, intent(in) ldz, real, dimension( ldqc, * ), intent(inout) qc, integer, intent(in) ldqc, real, dimension( ldzc, * ), intent(inout) zc, integer, intent(in) ldzc, real, dimension( * ), intent(inout) work, integer, intent(in) lwork, integer, intent(out) info)

SLAQZ4

Purpose:

     SLAQZ4 Executes a single multishift QZ sweep

Parameters
    ILSCHUR

              ILSCHUR is LOGICAL
                  Determines whether or not to update the full Schur form

    ILQ

              ILQ is LOGICAL
                  Determines whether or not to update the matrix Q

    ILZ

              ILZ is LOGICAL
                  Determines whether or not to update the matrix Z

    N

              N is INTEGER
              The order of the matrices A, B, Q, and Z.  N >= 0.

    ILO

              ILO is INTEGER

    IHI

              IHI is INTEGER

    NSHIFTS

              NSHIFTS is INTEGER
              The desired number of shifts to use

    NBLOCK_DESIRED

              NBLOCK_DESIRED is INTEGER
              The desired size of the computational windows

    SR

              SR is REAL array. SR contains
              the real parts of the shifts to use.

    SI

              SI is REAL array. SI contains
              the imaginary parts of the shifts to use.

    SS

              SS is REAL array. SS contains
              the scale of the shifts to use.

    A

              A is REAL array, dimension (LDA, N)

    LDA

              LDA is INTEGER
              The leading dimension of the array A.  LDA >= max( 1, N ).

    B

              B is REAL array, dimension (LDB, N)

    LDB

              LDB is INTEGER
              The leading dimension of the array B.  LDB >= max( 1, N ).

    Q

              Q is REAL array, dimension (LDQ, N)

    LDQ

              LDQ is INTEGER

    Z

              Z is REAL array, dimension (LDZ, N)

    LDZ

              LDZ is INTEGER

    QC

              QC is REAL array, dimension (LDQC, NBLOCK_DESIRED)

    LDQC

              LDQC is INTEGER

    ZC

              ZC is REAL array, dimension (LDZC, NBLOCK_DESIRED)

    LDZC

              LDZ is INTEGER

    WORK

              WORK is REAL array, dimension (MAX(1,LWORK))
              On exit, if INFO >= 0, WORK(1) returns the optimal LWORK.

    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.

    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

Definition at line 210 of file slaqz4.f.

Author

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