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

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

10       SUBROUTINE SORGTR( UPLO, N, A, LDA, TAU, WORK, LWORK, INFO )
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12           CHARACTER      UPLO
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14           INTEGER        INFO, LDA, LWORK, N
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16           REAL           A( LDA, * ), TAU( * ), WORK( * )
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PURPOSE

19       SORGTR generates a real orthogonal matrix Q which  is  defined  as  the
20       product of n-1 elementary reflectors of order N, as returned by SSYTRD:
21       if UPLO = 'U', Q = H(n-1) . . . H(2) H(1),
22       if UPLO = 'L', Q = H(1) H(2) . . . H(n-1).
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ARGUMENTS

25       UPLO    (input) CHARACTER*1
26               = 'U': Upper triangle of A contains elementary reflectors  from
27               SSYTRD;  = 'L': Lower triangle of A contains elementary reflec‐
28               tors from SSYTRD.
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30       N       (input) INTEGER
31               The order of the matrix Q. N >= 0.
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33       A       (input/output) REAL array, dimension (LDA,N)
34               On entry, the vectors which define the  elementary  reflectors,
35               as  returned  by SSYTRD.  On exit, the N-by-N orthogonal matrix
36               Q.
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38       LDA     (input) INTEGER
39               The leading dimension of the array A. LDA >= max(1,N).
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41       TAU     (input) REAL array, dimension (N-1)
42               TAU(i) must contain the scalar factor of the elementary reflec‐
43               tor H(i), as returned by SSYTRD.
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45       WORK    (workspace/output) REAL array, dimension (MAX(1,LWORK))
46               On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
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48       LWORK   (input) INTEGER
49               The  dimension  of  the  array  WORK. LWORK >= max(1,N-1).  For
50               optimum performance LWORK >= (N-1)*NB, where NB is the  optimal
51               blocksize.   If  LWORK = -1, then a workspace query is assumed;
52               the routine only calculates the optimal size of the WORK array,
53               returns this value as the first entry of the WORK array, and no
54               error message related to LWORK is issued by XERBLA.
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56       INFO    (output) INTEGER
57               = 0:  successful exit
58               < 0:  if INFO = -i, the i-th argument had an illegal value
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62 LAPACK routine (version 3.2)    November 2008                       SORGTR(1)
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