1CUNGHR(1)                LAPACK routine (version 3.2)                CUNGHR(1)
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NAME

6       CUNGHR  -  generates a complex unitary matrix Q which is defined as the
7       product of IHI-ILO elementary reflectors of order  N,  as  returned  by
8       CGEHRD
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SYNOPSIS

11       SUBROUTINE CUNGHR( N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO )
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13           INTEGER        IHI, ILO, INFO, LDA, LWORK, N
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15           COMPLEX        A( LDA, * ), TAU( * ), WORK( * )
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PURPOSE

18       CUNGHR  generates  a  complex  unitary matrix Q which is defined as the
19       product of IHI-ILO elementary reflectors of order  N,  as  returned  by
20       CGEHRD: Q = H(ilo) H(ilo+1) . . . H(ihi-1).
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ARGUMENTS

23       N       (input) INTEGER
24               The order of the matrix Q. N >= 0.
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26       ILO     (input) INTEGER
27               IHI      (input)  INTEGER ILO and IHI must have the same values
28               as in the previous call of CGEHRD.  Q  is  equal  to  the  unit
29               matrix  except  in  the submatrix Q(ilo+1:ihi,ilo+1:ihi).  1 <=
30               ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
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32       A       (input/output) COMPLEX array, dimension (LDA,N)
33               On entry, the vectors which define the  elementary  reflectors,
34               as returned by CGEHRD.  On exit, the N-by-N unitary matrix Q.
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36       LDA     (input) INTEGER
37               The leading dimension of the array A. LDA >= max(1,N).
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39       TAU     (input) COMPLEX array, dimension (N-1)
40               TAU(i) must contain the scalar factor of the elementary reflec‐
41               tor H(i), as returned by CGEHRD.
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43       WORK    (workspace/output) COMPLEX array, dimension (MAX(1,LWORK))
44               On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
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46       LWORK   (input) INTEGER
47               The dimension of the array WORK. LWORK >= IHI-ILO.  For optimum
48               performance  LWORK  >=  (IHI-ILO)*NB,  where  NB is the optimal
49               blocksize.  If LWORK = -1, then a workspace query  is  assumed;
50               the routine only calculates the optimal size of the WORK array,
51               returns this value as the first entry of the WORK array, and no
52               error message related to LWORK is issued by XERBLA.
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54       INFO    (output) INTEGER
55               = 0:  successful exit
56               < 0:  if INFO = -i, the i-th argument had an illegal value
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60 LAPACK routine (version 3.2)    November 2008                       CUNGHR(1)