NAME

       cungtr.f -

SYNOPSIS

   Functions/Subroutines
       subroutine cungtr (UPLO, N, A, LDA, TAU, WORK, LWORK, INFO)
           CUNGTR

Function/Subroutine Documentation

   subroutine cungtr (characterUPLO, integerN, complex, dimension( lda, * )A, integerLDA,
       complex, dimension( * )TAU, complex, dimension( * )WORK, integerLWORK, integerINFO)
       CUNGTR

       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).

       Parameters:
           UPLO

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

           N

                     N is INTEGER
                     The order of the matrix Q. N >= 0.

           A

                     A is 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

                     LDA is INTEGER
                     The leading dimension of the array A. LDA >= N.

           TAU

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

           WORK

                     WORK is COMPLEX array, dimension (MAX(1,LWORK))
                     On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

           LWORK

                     LWORK is INTEGER
                     The dimension of the array WORK. LWORK >= N-1.
                     For optimum performance LWORK >= (N-1)*NB, where NB is
                     the optimal blocksize.

                     If LWORK = -1, then a workspace query is assumed; the routine
                     only calculates the optimal size of the WORK array, returns
                     this value as the first entry of the WORK array, and no error
                     message related to LWORK is issued by XERBLA.

           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.

       Date:
           November 2011

       Definition at line 124 of file cungtr.f.

Author

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