LAPACK 3.12.0
LAPACK: Linear Algebra PACKage
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◆ cupgtr()

subroutine cupgtr ( character  uplo,
integer  n,
complex, dimension( * )  ap,
complex, dimension( * )  tau,
complex, dimension( ldq, * )  q,
integer  ldq,
complex, dimension( * )  work,
integer  info 
)

CUPGTR

Download CUPGTR + dependencies [TGZ] [ZIP] [TXT]

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).
Parameters
[in]UPLO
          UPLO is CHARACTER*1
          = 'U': Upper triangular packed storage used in previous
                 call to CHPTRD;
          = 'L': Lower triangular packed storage used in previous
                 call to CHPTRD.
[in]N
          N is INTEGER
          The order of the matrix Q. N >= 0.
[in]AP
          AP is COMPLEX array, dimension (N*(N+1)/2)
          The vectors which define the elementary reflectors, as
          returned by CHPTRD.
[in]TAU
          TAU is COMPLEX array, dimension (N-1)
          TAU(i) must contain the scalar factor of the elementary
          reflector H(i), as returned by CHPTRD.
[out]Q
          Q is COMPLEX array, dimension (LDQ,N)
          The N-by-N unitary matrix Q.
[in]LDQ
          LDQ is INTEGER
          The leading dimension of the array Q. LDQ >= max(1,N).
[out]WORK
          WORK is COMPLEX array, dimension (N-1)
[out]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.