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laqz4(3) LAPACK laqz4(3)

NAME

laqz4 - laqz4: step in ggev3, gges3

SYNOPSIS

Functions


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


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

SI


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

SS


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

A


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

LDA


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

B


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

LDB


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

Q


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

LDQ


LDQ is INTEGER

Z


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

LDZ


LDZ is INTEGER

QC


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

LDQC


LDQC is INTEGER

ZC


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

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

Author

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