laqz4 - Man Page

laqz4: step in ggev3, gges3

subroutine dlaqz4 (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)
DLAQZ4
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

Detailed Description

Function Documentation

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

Purpose:

 DLAQZ4 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 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 is DOUBLE PRECISION array. SR contains
          the real parts of the shifts to use.

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

          SS is DOUBLE PRECISION array. SS contains
          the scale of the shifts to use.

          A is DOUBLE PRECISION array, dimension (LDA, N)

LDA

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

          B is DOUBLE PRECISION array, dimension (LDB, N)

LDB

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

          Q is DOUBLE PRECISION array, dimension (LDQ, N)

LDQ

          LDQ is INTEGER

          Z is DOUBLE PRECISION array, dimension (LDZ, N)

LDZ

          LDZ is INTEGER

          QC is DOUBLE PRECISION array, dimension (LDQC, NBLOCK_DESIRED)

LDQC

          LDQC is INTEGER

          ZC is DOUBLE PRECISION array, dimension (LDZC, NBLOCK_DESIRED)

LDZC

          LDZ is INTEGER

WORK

          WORK is DOUBLE PRECISION 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 209 of file dlaqz4.f.

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