zunghr.f(3)

NAME
zunghr.f -

SYNOPSIS

  Functions/Subroutines

subroutine zunghr (N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO)
ZUNGHR

Function/Subroutine Documentation

  subroutine zunghr (integerN, integerILO, integerIHI, complex*16, dimension( lda, * )A, integerLDA, complex*16, dimension( * )TAU, complex*16, dimension( * )WORK, integerLWORK, integerINFO)

ZUNGHR

Purpose:

     ZUNGHR generates a complex unitary matrix Q which is defined as the
     product of IHI-ILO elementary reflectors of order N, as returned by
     ZGEHRD:

     Q = H(ilo) H(ilo+1) . . . H(ihi-1).

Parameters:
    N

              N is INTEGER
              The order of the matrix Q. N >= 0.

    ILO

              ILO is INTEGER

    IHI

              IHI is INTEGER

              ILO and IHI must have the same values as in the previous call
              of ZGEHRD. Q is equal to the unit matrix except in the
              submatrix Q(ilo+1:ihi,ilo+1:ihi).
              1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.

    A

              A is COMPLEX*16 array, dimension (LDA,N)
              On entry, the vectors which define the elementary reflectors,
              as returned by ZGEHRD.
              On exit, the N-by-N unitary matrix Q.

    LDA

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

    TAU

              TAU is COMPLEX*16 array, dimension (N-1)
              TAU(i) must contain the scalar factor of the elementary
              reflector H(i), as returned by ZGEHRD.

    WORK

              WORK is COMPLEX*16 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 >= IHI-ILO.
              For optimum performance LWORK >= (IHI-ILO)*NB, where NB is
              the optimal blocksize.

              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:
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Date:
    November 2011

Definition at line 127 of file zunghr.f.

Author

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