588 lines
17 KiB
Fortran
588 lines
17 KiB
Fortran
SUBROUTINE DLARFB( SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV,
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$ T, LDT, C, LDC, WORK, LDWORK )
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*
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* -- LAPACK auxiliary routine (version 2.0) --
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* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
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* Courant Institute, Argonne National Lab, and Rice University
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* February 29, 1992
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*
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* .. Scalar Arguments ..
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CHARACTER DIRECT, SIDE, STOREV, TRANS
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INTEGER K, LDC, LDT, LDV, LDWORK, M, N
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* ..
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* .. Array Arguments ..
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DOUBLE PRECISION C( LDC, * ), T( LDT, * ), V( LDV, * ),
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$ WORK( LDWORK, * )
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* ..
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*
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* Purpose
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* =======
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*
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* DLARFB applies a real block reflector H or its transpose H' to a
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* real m by n matrix C, from either the left or the right.
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*
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* Arguments
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* =========
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*
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* SIDE (input) CHARACTER*1
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* = 'L': apply H or H' from the Left
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* = 'R': apply H or H' from the Right
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*
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* TRANS (input) CHARACTER*1
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* = 'N': apply H (No transpose)
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* = 'T': apply H' (Transpose)
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*
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* DIRECT (input) CHARACTER*1
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* Indicates how H is formed from a product of elementary
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* reflectors
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* = 'F': H = H(1) H(2) . . . H(k) (Forward)
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* = 'B': H = H(k) . . . H(2) H(1) (Backward)
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*
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* STOREV (input) CHARACTER*1
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* Indicates how the vectors which define the elementary
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* reflectors are stored:
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* = 'C': Columnwise
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* = 'R': Rowwise
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*
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* M (input) INTEGER
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* The number of rows of the matrix C.
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*
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* N (input) INTEGER
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* The number of columns of the matrix C.
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*
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* K (input) INTEGER
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* The order of the matrix T (= the number of elementary
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* reflectors whose product defines the block reflector).
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*
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* V (input) DOUBLE PRECISION array, dimension
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* (LDV,K) if STOREV = 'C'
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* (LDV,M) if STOREV = 'R' and SIDE = 'L'
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* (LDV,N) if STOREV = 'R' and SIDE = 'R'
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* The matrix V. See further details.
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*
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* LDV (input) INTEGER
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* The leading dimension of the array V.
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* If STOREV = 'C' and SIDE = 'L', LDV >= max(1,M);
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* if STOREV = 'C' and SIDE = 'R', LDV >= max(1,N);
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* if STOREV = 'R', LDV >= K.
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*
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* T (input) DOUBLE PRECISION array, dimension (LDT,K)
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* The triangular k by k matrix T in the representation of the
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* block reflector.
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*
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* LDT (input) INTEGER
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* The leading dimension of the array T. LDT >= K.
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*
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* C (input/output) DOUBLE PRECISION array, dimension (LDC,N)
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* On entry, the m by n matrix C.
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* On exit, C is overwritten by H*C or H'*C or C*H or C*H'.
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*
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* LDC (input) INTEGER
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* The leading dimension of the array C. LDA >= max(1,M).
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*
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* WORK (workspace) DOUBLE PRECISION array, dimension (LDWORK,K)
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*
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* LDWORK (input) INTEGER
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* The leading dimension of the array WORK.
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* If SIDE = 'L', LDWORK >= max(1,N);
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* if SIDE = 'R', LDWORK >= max(1,M).
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*
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* =====================================================================
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*
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* .. Parameters ..
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DOUBLE PRECISION ONE
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PARAMETER ( ONE = 1.0D+0 )
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* ..
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* .. Local Scalars ..
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CHARACTER TRANST
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INTEGER I, J
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* ..
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* .. External Functions ..
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LOGICAL LSAME
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EXTERNAL LSAME
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* ..
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* .. External Subroutines ..
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EXTERNAL DCOPY, DGEMM, DTRMM
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* ..
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* .. Executable Statements ..
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*
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* Quick return if possible
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*
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IF( M.LE.0 .OR. N.LE.0 )
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$ RETURN
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*
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IF( LSAME( TRANS, 'N' ) ) THEN
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TRANST = 'T'
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ELSE
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TRANST = 'N'
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END IF
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*
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IF( LSAME( STOREV, 'C' ) ) THEN
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*
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IF( LSAME( DIRECT, 'F' ) ) THEN
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*
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* Let V = ( V1 ) (first K rows)
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* ( V2 )
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* where V1 is unit lower triangular.
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*
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IF( LSAME( SIDE, 'L' ) ) THEN
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*
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* Form H * C or H' * C where C = ( C1 )
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* ( C2 )
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*
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* W := C' * V = (C1'*V1 + C2'*V2) (stored in WORK)
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*
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* W := C1'
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*
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DO 10 J = 1, K
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CALL DCOPY( N, C( J, 1 ), LDC, WORK( 1, J ), 1 )
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10 CONTINUE
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*
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* W := W * V1
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*
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CALL DTRMM( 'Right', 'Lower', 'No transpose', 'Unit', N,
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$ K, ONE, V, LDV, WORK, LDWORK )
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IF( M.GT.K ) THEN
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*
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* W := W + C2'*V2
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*
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CALL DGEMM( 'Transpose', 'No transpose', N, K, M-K,
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$ ONE, C( K+1, 1 ), LDC, V( K+1, 1 ), LDV,
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$ ONE, WORK, LDWORK )
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END IF
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*
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* W := W * T' or W * T
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*
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CALL DTRMM( 'Right', 'Upper', TRANST, 'Non-unit', N, K,
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$ ONE, T, LDT, WORK, LDWORK )
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*
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* C := C - V * W'
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*
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IF( M.GT.K ) THEN
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*
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* C2 := C2 - V2 * W'
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*
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CALL DGEMM( 'No transpose', 'Transpose', M-K, N, K,
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$ -ONE, V( K+1, 1 ), LDV, WORK, LDWORK, ONE,
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$ C( K+1, 1 ), LDC )
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END IF
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*
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* W := W * V1'
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*
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CALL DTRMM( 'Right', 'Lower', 'Transpose', 'Unit', N, K,
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$ ONE, V, LDV, WORK, LDWORK )
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*
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* C1 := C1 - W'
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*
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DO 30 J = 1, K
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DO 20 I = 1, N
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C( J, I ) = C( J, I ) - WORK( I, J )
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20 CONTINUE
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30 CONTINUE
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*
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ELSE IF( LSAME( SIDE, 'R' ) ) THEN
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*
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* Form C * H or C * H' where C = ( C1 C2 )
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*
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* W := C * V = (C1*V1 + C2*V2) (stored in WORK)
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*
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* W := C1
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*
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DO 40 J = 1, K
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CALL DCOPY( M, C( 1, J ), 1, WORK( 1, J ), 1 )
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40 CONTINUE
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*
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* W := W * V1
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*
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CALL DTRMM( 'Right', 'Lower', 'No transpose', 'Unit', M,
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$ K, ONE, V, LDV, WORK, LDWORK )
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IF( N.GT.K ) THEN
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*
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* W := W + C2 * V2
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*
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CALL DGEMM( 'No transpose', 'No transpose', M, K, N-K,
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$ ONE, C( 1, K+1 ), LDC, V( K+1, 1 ), LDV,
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$ ONE, WORK, LDWORK )
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END IF
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*
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* W := W * T or W * T'
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*
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CALL DTRMM( 'Right', 'Upper', TRANS, 'Non-unit', M, K,
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$ ONE, T, LDT, WORK, LDWORK )
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*
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* C := C - W * V'
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*
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IF( N.GT.K ) THEN
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*
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* C2 := C2 - W * V2'
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*
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CALL DGEMM( 'No transpose', 'Transpose', M, N-K, K,
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$ -ONE, WORK, LDWORK, V( K+1, 1 ), LDV, ONE,
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$ C( 1, K+1 ), LDC )
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END IF
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*
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* W := W * V1'
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*
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CALL DTRMM( 'Right', 'Lower', 'Transpose', 'Unit', M, K,
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$ ONE, V, LDV, WORK, LDWORK )
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*
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* C1 := C1 - W
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*
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DO 60 J = 1, K
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DO 50 I = 1, M
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C( I, J ) = C( I, J ) - WORK( I, J )
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50 CONTINUE
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60 CONTINUE
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END IF
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*
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ELSE
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*
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* Let V = ( V1 )
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* ( V2 ) (last K rows)
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* where V2 is unit upper triangular.
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*
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IF( LSAME( SIDE, 'L' ) ) THEN
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*
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* Form H * C or H' * C where C = ( C1 )
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* ( C2 )
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*
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* W := C' * V = (C1'*V1 + C2'*V2) (stored in WORK)
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*
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* W := C2'
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*
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DO 70 J = 1, K
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CALL DCOPY( N, C( M-K+J, 1 ), LDC, WORK( 1, J ), 1 )
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70 CONTINUE
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*
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* W := W * V2
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*
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CALL DTRMM( 'Right', 'Upper', 'No transpose', 'Unit', N,
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$ K, ONE, V( M-K+1, 1 ), LDV, WORK, LDWORK )
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IF( M.GT.K ) THEN
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*
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* W := W + C1'*V1
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*
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CALL DGEMM( 'Transpose', 'No transpose', N, K, M-K,
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$ ONE, C, LDC, V, LDV, ONE, WORK, LDWORK )
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END IF
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*
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* W := W * T' or W * T
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*
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CALL DTRMM( 'Right', 'Lower', TRANST, 'Non-unit', N, K,
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$ ONE, T, LDT, WORK, LDWORK )
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*
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* C := C - V * W'
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*
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IF( M.GT.K ) THEN
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*
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* C1 := C1 - V1 * W'
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*
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CALL DGEMM( 'No transpose', 'Transpose', M-K, N, K,
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$ -ONE, V, LDV, WORK, LDWORK, ONE, C, LDC )
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END IF
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*
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* W := W * V2'
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*
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CALL DTRMM( 'Right', 'Upper', 'Transpose', 'Unit', N, K,
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$ ONE, V( M-K+1, 1 ), LDV, WORK, LDWORK )
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*
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* C2 := C2 - W'
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*
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DO 90 J = 1, K
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DO 80 I = 1, N
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C( M-K+J, I ) = C( M-K+J, I ) - WORK( I, J )
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80 CONTINUE
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90 CONTINUE
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*
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ELSE IF( LSAME( SIDE, 'R' ) ) THEN
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*
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* Form C * H or C * H' where C = ( C1 C2 )
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*
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* W := C * V = (C1*V1 + C2*V2) (stored in WORK)
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*
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* W := C2
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*
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DO 100 J = 1, K
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CALL DCOPY( M, C( 1, N-K+J ), 1, WORK( 1, J ), 1 )
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100 CONTINUE
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*
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* W := W * V2
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*
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CALL DTRMM( 'Right', 'Upper', 'No transpose', 'Unit', M,
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$ K, ONE, V( N-K+1, 1 ), LDV, WORK, LDWORK )
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IF( N.GT.K ) THEN
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*
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* W := W + C1 * V1
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*
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CALL DGEMM( 'No transpose', 'No transpose', M, K, N-K,
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$ ONE, C, LDC, V, LDV, ONE, WORK, LDWORK )
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END IF
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*
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* W := W * T or W * T'
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*
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CALL DTRMM( 'Right', 'Lower', TRANS, 'Non-unit', M, K,
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$ ONE, T, LDT, WORK, LDWORK )
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*
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* C := C - W * V'
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*
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IF( N.GT.K ) THEN
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*
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* C1 := C1 - W * V1'
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*
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CALL DGEMM( 'No transpose', 'Transpose', M, N-K, K,
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$ -ONE, WORK, LDWORK, V, LDV, ONE, C, LDC )
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END IF
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*
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* W := W * V2'
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*
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CALL DTRMM( 'Right', 'Upper', 'Transpose', 'Unit', M, K,
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$ ONE, V( N-K+1, 1 ), LDV, WORK, LDWORK )
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*
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* C2 := C2 - W
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*
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DO 120 J = 1, K
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DO 110 I = 1, M
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C( I, N-K+J ) = C( I, N-K+J ) - WORK( I, J )
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110 CONTINUE
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120 CONTINUE
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END IF
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END IF
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*
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ELSE IF( LSAME( STOREV, 'R' ) ) THEN
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*
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IF( LSAME( DIRECT, 'F' ) ) THEN
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*
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* Let V = ( V1 V2 ) (V1: first K columns)
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* where V1 is unit upper triangular.
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*
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IF( LSAME( SIDE, 'L' ) ) THEN
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*
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* Form H * C or H' * C where C = ( C1 )
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* ( C2 )
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*
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* W := C' * V' = (C1'*V1' + C2'*V2') (stored in WORK)
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*
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* W := C1'
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*
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DO 130 J = 1, K
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CALL DCOPY( N, C( J, 1 ), LDC, WORK( 1, J ), 1 )
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130 CONTINUE
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*
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* W := W * V1'
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*
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CALL DTRMM( 'Right', 'Upper', 'Transpose', 'Unit', N, K,
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$ ONE, V, LDV, WORK, LDWORK )
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IF( M.GT.K ) THEN
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*
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* W := W + C2'*V2'
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*
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CALL DGEMM( 'Transpose', 'Transpose', N, K, M-K, ONE,
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$ C( K+1, 1 ), LDC, V( 1, K+1 ), LDV, ONE,
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$ WORK, LDWORK )
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END IF
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*
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* W := W * T' or W * T
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*
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CALL DTRMM( 'Right', 'Upper', TRANST, 'Non-unit', N, K,
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$ ONE, T, LDT, WORK, LDWORK )
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*
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* C := C - V' * W'
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*
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IF( M.GT.K ) THEN
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*
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* C2 := C2 - V2' * W'
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*
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CALL DGEMM( 'Transpose', 'Transpose', M-K, N, K, -ONE,
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$ V( 1, K+1 ), LDV, WORK, LDWORK, ONE,
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$ C( K+1, 1 ), LDC )
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END IF
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*
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* W := W * V1
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*
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CALL DTRMM( 'Right', 'Upper', 'No transpose', 'Unit', N,
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$ K, ONE, V, LDV, WORK, LDWORK )
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*
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* C1 := C1 - W'
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*
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DO 150 J = 1, K
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DO 140 I = 1, N
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C( J, I ) = C( J, I ) - WORK( I, J )
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140 CONTINUE
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150 CONTINUE
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*
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ELSE IF( LSAME( SIDE, 'R' ) ) THEN
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*
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* Form C * H or C * H' where C = ( C1 C2 )
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*
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* W := C * V' = (C1*V1' + C2*V2') (stored in WORK)
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*
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* W := C1
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*
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DO 160 J = 1, K
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CALL DCOPY( M, C( 1, J ), 1, WORK( 1, J ), 1 )
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160 CONTINUE
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*
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* W := W * V1'
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*
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CALL DTRMM( 'Right', 'Upper', 'Transpose', 'Unit', M, K,
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$ ONE, V, LDV, WORK, LDWORK )
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IF( N.GT.K ) THEN
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*
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* W := W + C2 * V2'
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*
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CALL DGEMM( 'No transpose', 'Transpose', M, K, N-K,
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$ ONE, C( 1, K+1 ), LDC, V( 1, K+1 ), LDV,
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$ ONE, WORK, LDWORK )
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END IF
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*
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* W := W * T or W * T'
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*
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CALL DTRMM( 'Right', 'Upper', TRANS, 'Non-unit', M, K,
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$ ONE, T, LDT, WORK, LDWORK )
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*
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* C := C - W * V
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*
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IF( N.GT.K ) THEN
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*
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* C2 := C2 - W * V2
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*
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CALL DGEMM( 'No transpose', 'No transpose', M, N-K, K,
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$ -ONE, WORK, LDWORK, V( 1, K+1 ), LDV, ONE,
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$ C( 1, K+1 ), LDC )
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END IF
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*
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* W := W * V1
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*
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CALL DTRMM( 'Right', 'Upper', 'No transpose', 'Unit', M,
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$ K, ONE, V, LDV, WORK, LDWORK )
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*
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* C1 := C1 - W
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*
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DO 180 J = 1, K
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DO 170 I = 1, M
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C( I, J ) = C( I, J ) - WORK( I, J )
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170 CONTINUE
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180 CONTINUE
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*
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END IF
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*
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ELSE
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*
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* Let V = ( V1 V2 ) (V2: last K columns)
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* where V2 is unit lower triangular.
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*
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IF( LSAME( SIDE, 'L' ) ) THEN
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*
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* Form H * C or H' * C where C = ( C1 )
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* ( C2 )
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*
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* W := C' * V' = (C1'*V1' + C2'*V2') (stored in WORK)
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*
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* W := C2'
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*
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DO 190 J = 1, K
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CALL DCOPY( N, C( M-K+J, 1 ), LDC, WORK( 1, J ), 1 )
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190 CONTINUE
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*
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* W := W * V2'
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*
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CALL DTRMM( 'Right', 'Lower', 'Transpose', 'Unit', N, K,
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$ ONE, V( 1, M-K+1 ), LDV, WORK, LDWORK )
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|
IF( M.GT.K ) THEN
|
|
*
|
|
* W := W + C1'*V1'
|
|
*
|
|
CALL DGEMM( 'Transpose', 'Transpose', N, K, M-K, ONE,
|
|
$ C, LDC, V, LDV, ONE, WORK, LDWORK )
|
|
END IF
|
|
*
|
|
* W := W * T' or W * T
|
|
*
|
|
CALL DTRMM( 'Right', 'Lower', TRANST, 'Non-unit', N, K,
|
|
$ ONE, T, LDT, WORK, LDWORK )
|
|
*
|
|
* C := C - V' * W'
|
|
*
|
|
IF( M.GT.K ) THEN
|
|
*
|
|
* C1 := C1 - V1' * W'
|
|
*
|
|
CALL DGEMM( 'Transpose', 'Transpose', M-K, N, K, -ONE,
|
|
$ V, LDV, WORK, LDWORK, ONE, C, LDC )
|
|
END IF
|
|
*
|
|
* W := W * V2
|
|
*
|
|
CALL DTRMM( 'Right', 'Lower', 'No transpose', 'Unit', N,
|
|
$ K, ONE, V( 1, M-K+1 ), LDV, WORK, LDWORK )
|
|
*
|
|
* C2 := C2 - W'
|
|
*
|
|
DO 210 J = 1, K
|
|
DO 200 I = 1, N
|
|
C( M-K+J, I ) = C( M-K+J, I ) - WORK( I, J )
|
|
200 CONTINUE
|
|
210 CONTINUE
|
|
*
|
|
ELSE IF( LSAME( SIDE, 'R' ) ) THEN
|
|
*
|
|
* Form C * H or C * H' where C = ( C1 C2 )
|
|
*
|
|
* W := C * V' = (C1*V1' + C2*V2') (stored in WORK)
|
|
*
|
|
* W := C2
|
|
*
|
|
DO 220 J = 1, K
|
|
CALL DCOPY( M, C( 1, N-K+J ), 1, WORK( 1, J ), 1 )
|
|
220 CONTINUE
|
|
*
|
|
* W := W * V2'
|
|
*
|
|
CALL DTRMM( 'Right', 'Lower', 'Transpose', 'Unit', M, K,
|
|
$ ONE, V( 1, N-K+1 ), LDV, WORK, LDWORK )
|
|
IF( N.GT.K ) THEN
|
|
*
|
|
* W := W + C1 * V1'
|
|
*
|
|
CALL DGEMM( 'No transpose', 'Transpose', M, K, N-K,
|
|
$ ONE, C, LDC, V, LDV, ONE, WORK, LDWORK )
|
|
END IF
|
|
*
|
|
* W := W * T or W * T'
|
|
*
|
|
CALL DTRMM( 'Right', 'Lower', TRANS, 'Non-unit', M, K,
|
|
$ ONE, T, LDT, WORK, LDWORK )
|
|
*
|
|
* C := C - W * V
|
|
*
|
|
IF( N.GT.K ) THEN
|
|
*
|
|
* C1 := C1 - W * V1
|
|
*
|
|
CALL DGEMM( 'No transpose', 'No transpose', M, N-K, K,
|
|
$ -ONE, WORK, LDWORK, V, LDV, ONE, C, LDC )
|
|
END IF
|
|
*
|
|
* W := W * V2
|
|
*
|
|
CALL DTRMM( 'Right', 'Lower', 'No transpose', 'Unit', M,
|
|
$ K, ONE, V( 1, N-K+1 ), LDV, WORK, LDWORK )
|
|
*
|
|
* C1 := C1 - W
|
|
*
|
|
DO 240 J = 1, K
|
|
DO 230 I = 1, M
|
|
C( I, N-K+J ) = C( I, N-K+J ) - WORK( I, J )
|
|
230 CONTINUE
|
|
240 CONTINUE
|
|
*
|
|
END IF
|
|
*
|
|
END IF
|
|
END IF
|
|
*
|
|
RETURN
|
|
*
|
|
* End of DLARFB
|
|
*
|
|
END
|