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NAME
     cupgtr - generate  a  complex  unitary  matrix  Q  which  is
     defined  as the product of n-1 elementary reflectors H(i) of
     order n, as returned by CHPTRD using packed storage

SYNOPSIS
     SUBROUTINE CUPGTR( UPLO, N, AP, TAU, Q, LDQ, WORK, INFO )

     CHARACTER UPLO

     INTEGER INFO, LDQ, N

     COMPLEX AP( * ), Q( LDQ, * ), TAU( * ), WORK( * )



     #include <sunperf.h>

     void cupgtr(char uplo, int n, complex  *cap,  complex  *tau,
               complex *q, int ldq, int *info) ;

PURPOSE
     CUPGTR generates a complex unitary matrix Q which is defined
     as the product of n-1 elementary reflectors H(i) of order n,
     as returned by CHPTRD using packed storage:

     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 triangular  packed  storage  used  in
               previous  call  to CHPTRD; = 'L': Lower triangular
               packed storage used in previous call to CHPTRD.

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

     AP        (input) COMPLEX array, dimension (N*(N+1)/2)
               The vectors which define  the  elementary  reflec-
               tors, as returned by CHPTRD.

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

     Q         (output) COMPLEX array, dimension (LDQ,N)
               The N-by-N unitary matrix Q.

     LDQ       (input) INTEGER
               The leading dimension  of  the  array  Q.  LDQ  >=
               max(1,N).

     WORK      (workspace) COMPLEX array, dimension (N-1)

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

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