zunghr.f3

!>
!> 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).
!> 

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
!> 

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.