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NAME
     zunghr - generate  a  complex  unitary  matrix  Q  which  is
     defined  as  the product of IHI-ILO elementary reflectors of
     order N, as returned by ZGEHRD

SYNOPSIS
     SUBROUTINE ZUNGHR( N, ILO, IHI, A, LDA,  TAU,  WORK,  LWORK,
               INFO )

     INTEGER IHI, ILO, INFO, LDA, LWORK, N

     COMPLEX*16 A( LDA, * ), TAU( * ), WORK( LWORK )



     #include <sunperf.h>

     void zunghr(int n, int ilo, int ihi, doublecomplex *za,  int
               lda, doublecomplex *tau, int *info) ;

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).


ARGUMENTS
     N         (input) INTEGER
               The order of the matrix Q. N >= 0.

     ILO       (input) INTEGER
               IHI     (input) 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  subma-
               trix  Q(ilo+1:ihi,ilo+1:ihi).   1 <= ILO <= IHI <=
               N, if N > 0; ILO=1 and IHI=0, if N=0.

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

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

     WORK      (workspace/output)  COMPLEX*16  array,   dimension
               (LWORK)
               On exit, if INFO = 0, WORK(1) returns the  optimal
               LWORK.

     LWORK     (input) INTEGER
               The dimension of the array WORK. LWORK >= IHI-ILO.
               For  optimum  performance  LWORK  >= (IHI-ILO)*NB,
               where NB is the optimal blocksize.

     INFO      (output) INTEGER
               = 0:  successful exit
               < 0:  if INFO = -i, the i-th argument had an ille-
               gal value

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