Provided by: liblapack-doc_3.3.1-1_all bug

NAME

       LAPACK-3  -  generates  a  real orthogonal matrix Q which is defined as the product of n-1
       elementary reflectors of order N, as returned by DSYTRD

SYNOPSIS

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

           CHARACTER      UPLO

           INTEGER        INFO, LDA, LWORK, N

           DOUBLE         PRECISION A( LDA, * ), TAU( * ), WORK( * )

PURPOSE

       DORGTR generates a real orthogonal matrix Q  which  is  defined  as  the  product  of  n-1
       elementary reflectors of order N, as returned by DSYTRD:
        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 DSYTRD;
                = 'L': Lower triangle of A contains elementary reflectors
                from DSYTRD.

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

        A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
                On entry, the vectors which define the elementary reflectors,
                as returned by DSYTRD.
                On exit, the N-by-N orthogonal matrix Q.

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

        TAU     (input) DOUBLE PRECISION array, dimension (N-1)
                TAU(i) must contain the scalar factor of the elementary
                reflector H(i), as returned by DSYTRD.

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

        LWORK   (input) INTEGER
                The dimension of the array WORK. LWORK >= max(1,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    (output) INTEGER
                = 0:  successful exit
                < 0:  if INFO = -i, the i-th argument had an illegal value

 LAPACK routine (version 3.2)               April 2011                            DORGTR(3lapack)