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authorjason <jason@8a072113-8704-0410-8d35-dd094bca7971>2008-10-28 01:38:50 +0000
committerjason <jason@8a072113-8704-0410-8d35-dd094bca7971>2008-10-28 01:38:50 +0000
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Move LAPACK trunk into position.
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+ SUBROUTINE CGEQP3( M, N, A, LDA, JPVT, TAU, WORK, LWORK, RWORK,
+ $ INFO )
+*
+* -- LAPACK routine (version 3.1) --
+* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
+* November 2006
+*
+* .. Scalar Arguments ..
+ INTEGER INFO, LDA, LWORK, M, N
+* ..
+* .. Array Arguments ..
+ INTEGER JPVT( * )
+ REAL RWORK( * )
+ COMPLEX A( LDA, * ), TAU( * ), WORK( * )
+* ..
+*
+* Purpose
+* =======
+*
+* CGEQP3 computes a QR factorization with column pivoting of a
+* matrix A: A*P = Q*R using Level 3 BLAS.
+*
+* Arguments
+* =========
+*
+* M (input) INTEGER
+* The number of rows of the matrix A. M >= 0.
+*
+* N (input) INTEGER
+* The number of columns of the matrix A. N >= 0.
+*
+* A (input/output) COMPLEX array, dimension (LDA,N)
+* On entry, the M-by-N matrix A.
+* On exit, the upper triangle of the array contains the
+* min(M,N)-by-N upper trapezoidal matrix R; the elements below
+* the diagonal, together with the array TAU, represent the
+* unitary matrix Q as a product of min(M,N) elementary
+* reflectors.
+*
+* LDA (input) INTEGER
+* The leading dimension of the array A. LDA >= max(1,M).
+*
+* JPVT (input/output) INTEGER array, dimension (N)
+* On entry, if JPVT(J).ne.0, the J-th column of A is permuted
+* to the front of A*P (a leading column); if JPVT(J)=0,
+* the J-th column of A is a free column.
+* On exit, if JPVT(J)=K, then the J-th column of A*P was the
+* the K-th column of A.
+*
+* TAU (output) COMPLEX array, dimension (min(M,N))
+* The scalar factors of the elementary reflectors.
+*
+* WORK (workspace/output) COMPLEX 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 >= N+1.
+* For optimal 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.
+*
+* RWORK (workspace) REAL array, dimension (2*N)
+*
+* INFO (output) INTEGER
+* = 0: successful exit.
+* < 0: if INFO = -i, the i-th argument had an illegal value.
+*
+* Further Details
+* ===============
+*
+* The matrix Q is represented as a product of elementary reflectors
+*
+* Q = H(1) H(2) . . . H(k), where k = min(m,n).
+*
+* Each H(i) has the form
+*
+* H(i) = I - tau * v * v'
+*
+* where tau is a real/complex scalar, and v is a real/complex vector
+* with v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in
+* A(i+1:m,i), and tau in TAU(i).
+*
+* Based on contributions by
+* G. Quintana-Orti, Depto. de Informatica, Universidad Jaime I, Spain
+* X. Sun, Computer Science Dept., Duke University, USA
+*
+* =====================================================================
+*
+* .. Parameters ..
+ INTEGER INB, INBMIN, IXOVER
+ PARAMETER ( INB = 1, INBMIN = 2, IXOVER = 3 )
+* ..
+* .. Local Scalars ..
+ LOGICAL LQUERY
+ INTEGER FJB, IWS, J, JB, LWKOPT, MINMN, MINWS, NA, NB,
+ $ NBMIN, NFXD, NX, SM, SMINMN, SN, TOPBMN
+* ..
+* .. External Subroutines ..
+ EXTERNAL CGEQRF, CLAQP2, CLAQPS, CSWAP, CUNMQR, XERBLA
+* ..
+* .. External Functions ..
+ INTEGER ILAENV
+ REAL SCNRM2
+ EXTERNAL ILAENV, SCNRM2
+* ..
+* .. Intrinsic Functions ..
+ INTRINSIC INT, MAX, MIN
+* ..
+* .. Executable Statements ..
+*
+* Test input arguments
+* ====================
+*
+ INFO = 0
+ LQUERY = ( LWORK.EQ.-1 )
+ IF( M.LT.0 ) THEN
+ INFO = -1
+ ELSE IF( N.LT.0 ) THEN
+ INFO = -2
+ ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
+ INFO = -4
+ END IF
+*
+ IF( INFO.EQ.0 ) THEN
+ MINMN = MIN( M, N )
+ IF( MINMN.EQ.0 ) THEN
+ IWS = 1
+ LWKOPT = 1
+ ELSE
+ IWS = N + 1
+ NB = ILAENV( INB, 'CGEQRF', ' ', M, N, -1, -1 )
+ LWKOPT = ( N + 1 )*NB
+ END IF
+ WORK( 1 ) = LWKOPT
+*
+ IF( ( LWORK.LT.IWS ) .AND. .NOT.LQUERY ) THEN
+ INFO = -8
+ END IF
+ END IF
+*
+ IF( INFO.NE.0 ) THEN
+ CALL XERBLA( 'CGEQP3', -INFO )
+ RETURN
+ ELSE IF( LQUERY ) THEN
+ RETURN
+ END IF
+*
+* Quick return if possible.
+*
+ IF( MINMN.EQ.0 ) THEN
+ RETURN
+ END IF
+*
+* Move initial columns up front.
+*
+ NFXD = 1
+ DO 10 J = 1, N
+ IF( JPVT( J ).NE.0 ) THEN
+ IF( J.NE.NFXD ) THEN
+ CALL CSWAP( M, A( 1, J ), 1, A( 1, NFXD ), 1 )
+ JPVT( J ) = JPVT( NFXD )
+ JPVT( NFXD ) = J
+ ELSE
+ JPVT( J ) = J
+ END IF
+ NFXD = NFXD + 1
+ ELSE
+ JPVT( J ) = J
+ END IF
+ 10 CONTINUE
+ NFXD = NFXD - 1
+*
+* Factorize fixed columns
+* =======================
+*
+* Compute the QR factorization of fixed columns and update
+* remaining columns.
+*
+ IF( NFXD.GT.0 ) THEN
+ NA = MIN( M, NFXD )
+*CC CALL CGEQR2( M, NA, A, LDA, TAU, WORK, INFO )
+ CALL CGEQRF( M, NA, A, LDA, TAU, WORK, LWORK, INFO )
+ IWS = MAX( IWS, INT( WORK( 1 ) ) )
+ IF( NA.LT.N ) THEN
+*CC CALL CUNM2R( 'Left', 'Conjugate Transpose', M, N-NA,
+*CC $ NA, A, LDA, TAU, A( 1, NA+1 ), LDA, WORK,
+*CC $ INFO )
+ CALL CUNMQR( 'Left', 'Conjugate Transpose', M, N-NA, NA, A,
+ $ LDA, TAU, A( 1, NA+1 ), LDA, WORK, LWORK,
+ $ INFO )
+ IWS = MAX( IWS, INT( WORK( 1 ) ) )
+ END IF
+ END IF
+*
+* Factorize free columns
+* ======================
+*
+ IF( NFXD.LT.MINMN ) THEN
+*
+ SM = M - NFXD
+ SN = N - NFXD
+ SMINMN = MINMN - NFXD
+*
+* Determine the block size.
+*
+ NB = ILAENV( INB, 'CGEQRF', ' ', SM, SN, -1, -1 )
+ NBMIN = 2
+ NX = 0
+*
+ IF( ( NB.GT.1 ) .AND. ( NB.LT.SMINMN ) ) THEN
+*
+* Determine when to cross over from blocked to unblocked code.
+*
+ NX = MAX( 0, ILAENV( IXOVER, 'CGEQRF', ' ', SM, SN, -1,
+ $ -1 ) )
+*
+*
+ IF( NX.LT.SMINMN ) THEN
+*
+* Determine if workspace is large enough for blocked code.
+*
+ MINWS = ( SN+1 )*NB
+ IWS = MAX( IWS, MINWS )
+ IF( LWORK.LT.MINWS ) THEN
+*
+* Not enough workspace to use optimal NB: Reduce NB and
+* determine the minimum value of NB.
+*
+ NB = LWORK / ( SN+1 )
+ NBMIN = MAX( 2, ILAENV( INBMIN, 'CGEQRF', ' ', SM, SN,
+ $ -1, -1 ) )
+*
+*
+ END IF
+ END IF
+ END IF
+*
+* Initialize partial column norms. The first N elements of work
+* store the exact column norms.
+*
+ DO 20 J = NFXD + 1, N
+ RWORK( J ) = SCNRM2( SM, A( NFXD+1, J ), 1 )
+ RWORK( N+J ) = RWORK( J )
+ 20 CONTINUE
+*
+ IF( ( NB.GE.NBMIN ) .AND. ( NB.LT.SMINMN ) .AND.
+ $ ( NX.LT.SMINMN ) ) THEN
+*
+* Use blocked code initially.
+*
+ J = NFXD + 1
+*
+* Compute factorization: while loop.
+*
+*
+ TOPBMN = MINMN - NX
+ 30 CONTINUE
+ IF( J.LE.TOPBMN ) THEN
+ JB = MIN( NB, TOPBMN-J+1 )
+*
+* Factorize JB columns among columns J:N.
+*
+ CALL CLAQPS( M, N-J+1, J-1, JB, FJB, A( 1, J ), LDA,
+ $ JPVT( J ), TAU( J ), RWORK( J ),
+ $ RWORK( N+J ), WORK( 1 ), WORK( JB+1 ),
+ $ N-J+1 )
+*
+ J = J + FJB
+ GO TO 30
+ END IF
+ ELSE
+ J = NFXD + 1
+ END IF
+*
+* Use unblocked code to factor the last or only block.
+*
+*
+ IF( J.LE.MINMN )
+ $ CALL CLAQP2( M, N-J+1, J-1, A( 1, J ), LDA, JPVT( J ),
+ $ TAU( J ), RWORK( J ), RWORK( N+J ), WORK( 1 ) )
+*
+ END IF
+*
+ WORK( 1 ) = IWS
+ RETURN
+*
+* End of CGEQP3
+*
+ END