NAME

       sorgtr.f -

SYNOPSIS

   Functions/Subroutines
       subroutine sorgtr (UPLO, N, A, LDA, TAU, WORK, LWORK, INFO)
           SORGTR

Function/Subroutine Documentation

   subroutine sorgtr (character UPLO, integer N, real, dimension( lda, * ) A, integer LDA, real,
       dimension( * ) TAU, real, dimension( * ) WORK, integer LWORK, integer INFO)
       SORGTR

       Purpose:

            SORGTR generates a real orthogonal matrix Q which is defined as the
            product of n-1 elementary reflectors of order N, as returned by
            SSYTRD:

            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 SSYTRD;
                     = 'L': Lower triangle of A contains elementary reflectors
                            from SSYTRD.

           N

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

           A

                     A is REAL array, dimension (LDA,N)
                     On entry, the vectors which define the elementary reflectors,
                     as returned by SSYTRD.
                     On exit, the N-by-N orthogonal matrix Q.

           LDA

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

           TAU

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

           WORK

                     WORK is REAL 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 >= 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

                     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

Author

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