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NAME
     cungtr - generate  a  complex  unitary  matrix  Q  which  is
     defined as the product of n-1 elementary reflectors of order
     N, as returned by CHETRD

SYNOPSIS
     SUBROUTINE CUNGTR( UPLO, N, A, LDA, TAU, WORK, LWORK, INFO )

     CHARACTER UPLO

     INTEGER INFO, LDA, LWORK, N

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



     #include <sunperf.h>

     void cungtr(char uplo, int n, complex *ca, int lda,  complex
               *tau, int *info) ;

PURPOSE
     CUNGTR generates a complex unitary matrix Q which is defined
     as  the  product of n-1 elementary reflectors of order N, as
     returned by CHETRD:

     if UPLO = 'U', Q = H(n-1) . . . H(2) H(1),

     if UPLO = 'L', Q = H(1) H(2) . . . H(n-1).


ARGUMENTS
     UPLO      (input) CHARACTER*1
               = 'U': Upper triangle  of  A  contains  elementary
               reflectors from CHETRD; = 'L': Lower triangle of A
               contains elementary reflectors from CHETRD.

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

     A         (input/output) COMPLEX array, dimension (LDA,N)
               On entry, the vectors which define the  elementary
               reflectors,  as  returned by CHETRD.  On exit, the
               N-by-N unitary matrix Q.

     LDA       (input) INTEGER
               The leading dimension of the array A. LDA >= N.

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

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

     LWORK     (input) INTEGER
               The dimension of the array  WORK.  LWORK  >=  N-1.
               For  optimum  performance LWORK >= (N-1)*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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