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authorjulie <julielangou@users.noreply.github.com>2012-07-27 06:42:44 +0000
committerjulie <julielangou@users.noreply.github.com>2012-07-27 06:42:44 +0000
commit199c646448f65fb375a8aaf7383c705dab58f550 (patch)
tree5681fbfbb7d700a8a1da347fa25f90a2967c14a2 /SRC/dorbdb3.f
parent2a180a73cd84e5bfdd306d649e1713e144a6f132 (diff)
Commit Brian Sutton new CS Decomposition routines.
All the routines from the SRC folder have been updated to integrate the current Doxygen layout. Everything seems to be fine, all tests passed without problem.
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+*> \brief \b DORBDB3
+*
+* =========== DOCUMENTATION ===========
+*
+* Online html documentation available at
+* http://www.netlib.org/lapack/explore-html/
+*
+*> \htmlonly
+*> Download DORBDB3 + dependencies
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dorbdb3.f">
+*> [TGZ]</a>
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dorbdb3.f">
+*> [ZIP]</a>
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dorbdb3.f">
+*> [TXT]</a>
+*> \endhtmlonly
+*
+* Definition:
+* ===========
+*
+* SUBROUTINE DORBDB3( M, P, Q, X11, LDX11, X21, LDX21, THETA, PHI,
+* TAUP1, TAUP2, TAUQ1, WORK, LWORK, INFO )
+*
+* .. Scalar Arguments ..
+* INTEGER INFO, LWORK, M, P, Q, LDX11, LDX21
+* ..
+* .. Array Arguments ..
+* DOUBLE PRECISION PHI(*), THETA(*)
+* DOUBLE PRECISION TAUP1(*), TAUP2(*), TAUQ1(*), WORK(*),
+* $ X11(LDX11,*), X21(LDX21,*)
+* ..
+*
+*
+*> \par Purpose:
+*> =============
+*>
+*>\verbatim
+*>
+*> DORBDB3 simultaneously bidiagonalizes the blocks of a tall and skinny
+*> matrix X with orthonomal columns:
+*>
+*> [ B11 ]
+*> [ X11 ] [ P1 | ] [ 0 ]
+*> [-----] = [---------] [-----] Q1**T .
+*> [ X21 ] [ | P2 ] [ B21 ]
+*> [ 0 ]
+*>
+*> X11 is P-by-Q, and X21 is (M-P)-by-Q. M-P must be no larger than P,
+*> Q, or M-Q. Routines DORBDB1, DORBDB2, and DORBDB4 handle cases in
+*> which M-P is not the minimum dimension.
+*>
+*> The orthogonal matrices P1, P2, and Q1 are P-by-P, (M-P)-by-(M-P),
+*> and (M-Q)-by-(M-Q), respectively. They are represented implicitly by
+*> Householder vectors.
+*>
+*> B11 and B12 are (M-P)-by-(M-P) bidiagonal matrices represented
+*> implicitly by angles THETA, PHI.
+*>
+*>\endverbatim
+*
+* Arguments:
+* ==========
+*
+*> \param[in] M
+*> \verbatim
+*> M is INTEGER
+*> The number of rows X11 plus the number of rows in X21.
+*> \endverbatim
+*>
+*> \param[in] P
+*> \verbatim
+*> P is INTEGER
+*> The number of rows in X11. 0 <= P <= M. M-P <= min(P,Q,M-Q).
+*> \endverbatim
+*>
+*> \param[in] Q
+*> \verbatim
+*> Q is INTEGER
+*> The number of columns in X11 and X21. 0 <= Q <= M.
+*> \endverbatim
+*>
+*> \param[in,out] X11
+*> \verbatim
+*> X11 is DOUBLE PRECISION array, dimension (LDX11,Q)
+*> On entry, the top block of the matrix X to be reduced. On
+*> exit, the columns of tril(X11) specify reflectors for P1 and
+*> the rows of triu(X11,1) specify reflectors for Q1.
+*> \endverbatim
+*>
+*> \param[in] LDX11
+*> \verbatim
+*> LDX11 is INTEGER
+*> The leading dimension of X11. LDX11 >= P.
+*> \endverbatim
+*>
+*> \param[in,out] X21
+*> \verbatim
+*> X21 is DOUBLE PRECISION array, dimension (LDX21,Q)
+*> On entry, the bottom block of the matrix X to be reduced. On
+*> exit, the columns of tril(X21) specify reflectors for P2.
+*> \endverbatim
+*>
+*> \param[in] LDX21
+*> \verbatim
+*> LDX21 is INTEGER
+*> The leading dimension of X21. LDX21 >= M-P.
+*> \endverbatim
+*>
+*> \param[out] THETA
+*> \verbatim
+*> THETA is DOUBLE PRECISION array, dimension (Q)
+*> The entries of the bidiagonal blocks B11, B21 are defined by
+*> THETA and PHI. See Further Details.
+*> \endverbatim
+*>
+*> \param[out] PHI
+*> \verbatim
+*> PHI is DOUBLE PRECISION array, dimension (Q-1)
+*> The entries of the bidiagonal blocks B11, B21 are defined by
+*> THETA and PHI. See Further Details.
+*> \endverbatim
+*>
+*> \param[out] TAUP1
+*> \verbatim
+*> TAUP1 is DOUBLE PRECISION array, dimension (P)
+*> The scalar factors of the elementary reflectors that define
+*> P1.
+*> \endverbatim
+*>
+*> \param[out] TAUP2
+*> \verbatim
+*> TAUP2 is DOUBLE PRECISION array, dimension (M-P)
+*> The scalar factors of the elementary reflectors that define
+*> P2.
+*> \endverbatim
+*>
+*> \param[out] TAUQ1
+*> \verbatim
+*> TAUQ1 is DOUBLE PRECISION array, dimension (Q)
+*> The scalar factors of the elementary reflectors that define
+*> Q1.
+*> \endverbatim
+*>
+*> \param[out] WORK
+*> \verbatim
+*> WORK is DOUBLE PRECISION array, dimension (LWORK)
+*> \endverbatim
+*>
+*> \param[in] LWORK
+*> \verbatim
+*> LWORK is INTEGER
+*> The dimension of the array WORK. LWORK >= M-Q.
+*>
+*> 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.
+*> \endverbatim
+*>
+*> \param[out] INFO
+*> \verbatim
+*> INFO is INTEGER
+*> = 0: successful exit.
+*> < 0: if INFO = -i, the i-th argument had an illegal value.
+*> \endverbatim
+*
+* Authors:
+* ========
+*
+*> \author Univ. of Tennessee
+*> \author Univ. of California Berkeley
+*> \author Univ. of Colorado Denver
+*> \author NAG Ltd.
+*
+*> \date July 2012
+*
+*> \ingroup doubleOTHERcomputational
+*
+*> \par Further Details:
+* =====================
+*>
+*> \verbatim
+*>
+*> The upper-bidiagonal blocks B11, B21 are represented implicitly by
+*> angles THETA(1), ..., THETA(Q) and PHI(1), ..., PHI(Q-1). Every entry
+*> in each bidiagonal band is a product of a sine or cosine of a THETA
+*> with a sine or cosine of a PHI. See [1] or DORCSD for details.
+*>
+*> P1, P2, and Q1 are represented as products of elementary reflectors.
+*> See DORCSD2BY1 for details on generating P1, P2, and Q1 using DORGQR
+*> and DORGLQ.
+*> \endverbatim
+*
+*> \par References:
+* ================
+*>
+*> [1] Brian D. Sutton. Computing the complete CS decomposition. Numer.
+*> Algorithms, 50(1):33-65, 2009.
+*>
+* =====================================================================
+ SUBROUTINE DORBDB3( M, P, Q, X11, LDX11, X21, LDX21, THETA, PHI,
+ $ TAUP1, TAUP2, TAUQ1, WORK, LWORK, INFO )
+*
+* -- LAPACK computational routine (version 3.5.0) --
+* -- LAPACK is a software package provided by Univ. of Tennessee, --
+* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
+* July 2012
+*
+* .. Scalar Arguments ..
+ INTEGER INFO, LWORK, M, P, Q, LDX11, LDX21
+* ..
+* .. Array Arguments ..
+ DOUBLE PRECISION PHI(*), THETA(*)
+ DOUBLE PRECISION TAUP1(*), TAUP2(*), TAUQ1(*), WORK(*),
+ $ X11(LDX11,*), X21(LDX21,*)
+* ..
+*
+* ====================================================================
+*
+* .. Parameters ..
+ DOUBLE PRECISION ONE
+ PARAMETER ( ONE = 1.0D0 )
+* ..
+* .. Local Scalars ..
+ DOUBLE PRECISION C, S
+ INTEGER CHILDINFO, I, ILARF, IORBDB5, LLARF, LORBDB5,
+ $ LWORKMIN, LWORKOPT
+ LOGICAL LQUERY
+* ..
+* .. External Subroutines ..
+ EXTERNAL DLARF, DLARFGP, DORBDB5, DROT, XERBLA
+* ..
+* .. External Functions ..
+ DOUBLE PRECISION DNRM2
+ EXTERNAL DNRM2
+* ..
+* .. Intrinsic Function ..
+ INTRINSIC ATAN2, COS, MAX, SIN, SQRT
+* ..
+* .. Executable Statements ..
+*
+* Test input arguments
+*
+ INFO = 0
+ LQUERY = LWORK .EQ. -1
+*
+ IF( M .LT. 0 ) THEN
+ INFO = -1
+ ELSE IF( 2*P .LT. M .OR. P .GT. M ) THEN
+ INFO = -2
+ ELSE IF( Q .LT. M-P .OR. M-Q .LT. M-P ) THEN
+ INFO = -3
+ ELSE IF( LDX11 .LT. MAX( 1, P ) ) THEN
+ INFO = -5
+ ELSE IF( LDX21 .LT. MAX( 1, M-P ) ) THEN
+ INFO = -7
+ END IF
+*
+* Compute workspace
+*
+ IF( INFO .EQ. 0 ) THEN
+ ILARF = 2
+ LLARF = MAX( P, M-P-1, Q-1 )
+ IORBDB5 = 2
+ LORBDB5 = Q-1
+ LWORKOPT = MAX( ILARF+LLARF-1, IORBDB5+LORBDB5-1 )
+ LWORKMIN = LWORKOPT
+ WORK(1) = LWORKOPT
+ IF( LWORK .LT. LWORKMIN .AND. .NOT.LQUERY ) THEN
+ INFO = -14
+ END IF
+ END IF
+ IF( INFO .NE. 0 ) THEN
+ CALL XERBLA( 'DORBDB3', -INFO )
+ RETURN
+ ELSE IF( LQUERY ) THEN
+ RETURN
+ END IF
+*
+* Reduce rows 1, ..., M-P of X11 and X21
+*
+ DO I = 1, M-P
+*
+ IF( I .GT. 1 ) THEN
+ CALL DROT( Q-I+1, X11(I-1,I), LDX11, X21(I,I), LDX11, C, S )
+ END IF
+*
+ CALL DLARFGP( Q-I+1, X21(I,I), X21(I,I+1), LDX21, TAUQ1(I) )
+ S = X21(I,I)
+ X21(I,I) = ONE
+ CALL DLARF( 'R', P-I+1, Q-I+1, X21(I,I), LDX21, TAUQ1(I),
+ $ X11(I,I), LDX11, WORK(ILARF) )
+ CALL DLARF( 'R', M-P-I, Q-I+1, X21(I,I), LDX21, TAUQ1(I),
+ $ X21(I+1,I), LDX21, WORK(ILARF) )
+ C = SQRT( DNRM2( P-I+1, X11(I,I), 1, X11(I,I),
+ $ 1 )**2 + DNRM2( M-P-I, X21(I+1,I), 1, X21(I+1,I), 1 )**2 )
+ THETA(I) = ATAN2( S, C )
+*
+ CALL DORBDB5( P-I+1, M-P-I, Q-I, X11(I,I), 1, X21(I+1,I), 1,
+ $ X11(I,I+1), LDX11, X21(I+1,I+1), LDX21,
+ $ WORK(IORBDB5), LORBDB5, CHILDINFO )
+ CALL DLARFGP( P-I+1, X11(I,I), X11(I+1,I), 1, TAUP1(I) )
+ IF( I .LT. M-P ) THEN
+ CALL DLARFGP( M-P-I, X21(I+1,I), X21(I+2,I), 1, TAUP2(I) )
+ PHI(I) = ATAN2( X21(I+1,I), X11(I,I) )
+ C = COS( PHI(I) )
+ S = SIN( PHI(I) )
+ X21(I+1,I) = ONE
+ CALL DLARF( 'L', M-P-I, Q-I, X21(I+1,I), 1, TAUP2(I),
+ $ X21(I+1,I+1), LDX21, WORK(ILARF) )
+ END IF
+ X11(I,I) = ONE
+ CALL DLARF( 'L', P-I+1, Q-I, X11(I,I), 1, TAUP1(I), X11(I,I+1),
+ $ LDX11, WORK(ILARF) )
+*
+ END DO
+*
+* Reduce the bottom-right portion of X11 to the identity matrix
+*
+ DO I = M-P + 1, Q
+ CALL DLARFGP( P-I+1, X11(I,I), X11(I+1,I), 1, TAUP1(I) )
+ X11(I,I) = ONE
+ CALL DLARF( 'L', P-I+1, Q-I, X11(I,I), 1, TAUP1(I), X11(I,I+1),
+ $ LDX11, WORK(ILARF) )
+ END DO
+*
+ RETURN
+*
+* End of DORBDB3
+*
+ END
+