cunghr.f(3)

NAME
cunghr.f -

SYNOPSIS

  Functions/Subroutines
subroutine cunghr (N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO)
CUNGHR

Function/Subroutine Documentation

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

CUNGHR

Purpose:

     CUNGHR generates a complex unitary matrix Q which is defined as the
     product of IHI-ILO elementary reflectors of order N, as returned by
     CGEHRD:
     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 CGEHRD. 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 array, dimension (LDA,N)
              On entry, the vectors which define the elementary reflectors,
              as returned by CGEHRD.
              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 array, dimension (N-1)
              TAU(i) must contain the scalar factor of the elementary
              reflector H(i), as returned by CGEHRD.

    WORK

              WORK is COMPLEX 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 cunghr.f.

Author

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